Just got a bunch of instances of this suite timing out all on Windows agents. Could be a coincidence but seems unlikely.

**Build scan:**
https://gradle-enterprise.elastic.co/s/rvfpi7upehqjk/tests/:x-pack:plugin:esql:test/org.elasticsearch.xpack.esql.expression.function.scalar.nulls.CoalesceTests
**Reproduction line:**
```
null
```

**Applicable branches:**
main

**Reproduces locally?:**
Didn't try

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.esql.expression.function.scalar.nulls.CoalesceTests&tests.test=classMethod
**Failure excerpt:**
```
java.lang.Exception: Suite timeout exceeded (>= 2400000 msec).

  at __randomizedtesting.SeedInfo.seed([546AEE28130887AC]:0)

```
x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/AbstractFunctionTestCase.java
if (definition == null) {
            LogManager.getLogger(getTestClass()).info("Skipping rendering signature because the function isn't registered");
            return;
        }
        String rendered = RailRoadDiagram.functionSignature(definition);
        LogManager.getLogger(getTestClass()).info("Writing function signature");
        writeToTempDir("signature", rendered, "svg");
    }
    /**
     * Unique signatures encountered by this test.
     * <p>
     *     We clear this at the beginning of the test class with
     *     {@link #clearSignatures} out of paranoia. It <strong>is</strong>
     *     shared by many tests, after all.
     * </p>
     * <p>
     *     After each test method we add the signature it operated on via
     *     {@link #trackSignature}. Once the test class is done we render
     *     all the unique signatures to a temp file with {@link #renderTypesTable}.
     *     We use a temp file because that's all we're allowed to write to.
     *     Gradle will move the files into the docs after this is done.
     * </p>
     */
    private static final Map<List<DataType>, DataType> signatures = new HashMap<>();
    @BeforeClass
    public static void clearSignatures() {
        signatures.clear();
    }
    @After
    public void trackSignature() {