I think this test started failing when #96224 got merged?

**Build scan:**
https://gradle-enterprise.elastic.co/s/eocgfxmszp332/tests/:server:test/org.elasticsearch.search.internal.ShardSearchRequestTests/testForceSyntheticUnsupported

**Reproduction line:**
```
./gradlew ':server:test' --tests "org.elasticsearch.search.internal.ShardSearchRequestTests.testForceSyntheticUnsupported" -Dtests.seed=682CDD108409D789 -Dtests.locale=sv -Dtests.timezone=Asia/Ulan_Bator -Druntime.java=20
```

**Applicable branches:**
main

**Reproduces locally?:**
Yes

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.search.internal.ShardSearchRequestTests&tests.test=testForceSyntheticUnsupported

**Failure excerpt:**
```
org.junit.ComparisonFailure: expected:<[cannot serialize [sub_searches] to version [8030099]]> but was:<[force_synthetic_source is not supported before 8.4.0]>

  at __randomizedtesting.SeedInfo.seed([682CDD108409D789:84F9A71AB60DC34F]:0)
  at org.junit.Assert.assertEquals(Assert.java:115)
  at org.junit.Assert.assertEquals(Assert.java:144)
  at org.elasticsearch.search.internal.ShardSearchRequestTests.testForceSyntheticUnsupported(ShardSearchRequestTests.java:270)
  at jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
  at java.lang.reflect.Method.invoke(Method.java:578)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.invoke(RandomizedRunner.java:1758)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$8.evaluate(RandomizedRunner.java:946)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$9.evaluate(RandomizedRunner.java:982)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$10.evaluate(RandomizedRunner.java:996)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleSetupTeardownChained$1.evaluate(TestRuleSetupTeardownChained.java:48)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleThreadAndTestName$1.evaluate(TestRuleThreadAndTestName.java:45)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.forkTimeoutingTask(ThreadLeakControl.java:843)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$3.evaluate(ThreadLeakControl.java:490)
  at com.carrotsearch.randomizedtesting.RandomizedRunner.runSingleTest(RandomizedRunner.java:955)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$5.evaluate(RandomizedRunner.java:840)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$6.evaluate(RandomizedRunner.java:891)
  at com.carrotsearch.randomizedtesting.RandomizedRunner$7.evaluate(RandomizedRunner.java:902)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleStoreClassName$1.evaluate(TestRuleStoreClassName.java:38)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.NoShadowingOrOverridesOnMethodsRule$1.evaluate(NoShadowingOrOverridesOnMethodsRule.java:40)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at org.apache.lucene.tests.util.TestRuleAssertionsRequired$1.evaluate(TestRuleAssertionsRequired.java:53)
  at org.apache.lucene.tests.util.AbstractBeforeAfterRule$1.evaluate(AbstractBeforeAfterRule.java:43)
  at org.apache.lucene.tests.util.TestRuleMarkFailure$1.evaluate(TestRuleMarkFailure.java:44)
  at org.apache.lucene.tests.util.TestRuleIgnoreAfterMaxFailures$1.evaluate(TestRuleIgnoreAfterMaxFailures.java:60)
  at org.apache.lucene.tests.util.TestRuleIgnoreTestSuites$1.evaluate(TestRuleIgnoreTestSuites.java:47)
  at com.carrotsearch.randomizedtesting.rules.StatementAdapter.evaluate(StatementAdapter.java:36)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl$StatementRunner.run(ThreadLeakControl.java:390)
  at com.carrotsearch.randomizedtesting.ThreadLeakControl.lambda$forkTimeoutingTask$0(ThreadLeakControl.java:850)
  at java.lang.Thread.run(Thread.java:1623)

```
server/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java
out.writeOptionalWriteable(pointInTimeBuilder);
        }
        if (out.getTransportVersion().onOrAfter(TransportVersion.V_7_11_0)) {
            out.writeGenericMap(runtimeMappings);
        } else {
            if (false == runtimeMappings.isEmpty()) {
                throw new IllegalArgumentException(
                    "Versions before 7110099 don't support [runtime_mappings] and search was sent to [" + out.getTransportVersion() + "]"
                );
            }
        }
        if (out.getTransportVersion().onOrAfter(TransportVersion.V_8_4_0)) {
            if (out.getTransportVersion().before(TransportVersion.V_8_7_0)) {
                if (knnSearch.size() > 1) {
                    throw new IllegalArgumentException(
                        "Versions before 8070099 don't support multiple [knn] search clauses and search was sent to ["
                            + out.getTransportVersion()
                            + "]"
                    );
                }
                out.writeOptionalWriteable(knnSearch.isEmpty() ? null : knnSearch.get(0));
            } else {
                out.writeCollection(knnSearch);
            }
        }
        if (out.getTransportVersion().onOrAfter(TransportVersion.V_8_8_0)) {
            out.writeOptionalNamedWriteable(rankBuilder);
        } else if (rankBuilder != null) {
            throw new IllegalArgumentException("cannot serialize [rank] to version [" + out.getTransportVersion() + "]");
        }