**Build scan:**
https://gradle-enterprise.elastic.co/s/whiwuz23mtmvq/tests/:x-pack:plugin:rollup:test/org.elasticsearch.xpack.rollup.v2.RollupActionSingleNodeTests/testCannotRollupToExistingIndex

**Reproduction line:**
`./gradlew ':x-pack:plugin:rollup:test' --tests "org.elasticsearch.xpack.rollup.v2.RollupActionSingleNodeTests.testCannotRollupToExistingIndex" -Dtests.seed=9814B01249EAC77D -Dtests.locale=en-SG -Dtests.timezone=Africa/Windhoek -Druntime.java=17`

**Applicable branches:**
main

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

**Failure history:**
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.xpack.rollup.v2.RollupActionSingleNodeTests&tests.test=testCannotRollupToExistingIndex

**Failure excerpt:**
```
org.elasticsearch.index.IndexNotFoundException: no such index [rollup-testcannotrollupwhileotherrollupinprogress-svlo]

  at __randomizedtesting.SeedInfo.seed([9814B01249EAC77D:325B86553CE92325]:0)
  at org.elasticsearch.cluster.metadata.Metadata.getIndexSafe(Metadata.java:919)
  at org.elasticsearch.cluster.metadata.MetadataDeleteIndexService.deleteIndices(MetadataDeleteIndexService.java:89)
  at org.elasticsearch.cluster.metadata.MetadataDeleteIndexService$1.execute(MetadataDeleteIndexService.java:70)
  at org.elasticsearch.cluster.service.MasterService$UnbatchedExecutor.execute(MasterService.java:515)
  at org.elasticsearch.cluster.service.MasterService.innerExecuteTasks(MasterService.java:959)
  at org.elasticsearch.cluster.service.MasterService.executeTasks(MasterService.java:929)
  at org.elasticsearch.cluster.service.MasterService.runTasks(MasterService.java:261)
  at org.elasticsearch.cluster.service.MasterService$Batcher.run(MasterService.java:165)
  at org.elasticsearch.cluster.service.TaskBatcher.runIfNotProcessed(TaskBatcher.java:110)
  at org.elasticsearch.cluster.service.TaskBatcher$BatchedTask.run(TaskBatcher.java:148)
  at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingRunnable.run(ThreadContext.java:710)
  at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.runAndClean(PrioritizedEsThreadPoolExecutor.java:257)
  at org.elasticsearch.common.util.concurrent.PrioritizedEsThreadPoolExecutor$TieBreakingPrioritizedRunnable.run(PrioritizedEsThreadPoolExecutor.java:223)
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
  at java.lang.Thread.run(Thread.java:833)

```
x-pack/plugin/rollup/src/test/java/org/elasticsearch/xpack/rollup/v2/RollupActionSingleNodeTests.java
String rollupIndex = "rollup-" + sourceIndex;
        rollup(sourceIndex, rollupIndex, config);
        assertRollupIndex(sourceIndex, rollupIndex, config);
        var r = client().execute(GetDataStreamAction.INSTANCE, new GetDataStreamAction.Request(new String[] { dataStreamName })).get();
        assertEquals(1, r.getDataStreams().size());
        List<Index> indices = r.getDataStreams().get(0).getDataStream().getIndices();
        
        assertTrue(indices.stream().filter(i -> i.getName().equals(rollupIndex)).toList().isEmpty());
        
        assertFalse(indices.stream().filter(i -> i.getName().equals(sourceIndex)).toList().isEmpty());
    }
    private DateHistogramInterval randomInterval() {
        return ConfigTestHelpers.randomInterval();
    }
    private String randomDateForInterval(DateHistogramInterval interval) {
        long endTime = startTime + MAX_NUM_BUCKETS * interval.estimateMillis();
        return randomDateForRange(startTime, endTime);
    }
    private String randomDateForRange(long start, long end) {
        return DATE_FORMATTER.formatMillis(randomLongBetween(start, end));
    }
    private void bulkIndex(SourceSupplier sourceSupplier) throws IOException {
        bulkIndex(sourceIndex, sourceSupplier);
    }
    private void bulkIndex(String indexName, SourceSupplier sourceSupplier) throws IOException {
        BulkRequestBuilder bulkRequestBuilder = client().prepareBulk();
        bulkRequestBuilder.setRefreshPolicy(WriteRequest.RefreshPolicy.IMMEDIATE);
        for (int i = 0; i < docCount; i++) {
            IndexRequest indexRequest = new IndexRequest(indexName).opType(DocWriteRequest.OpType.CREATE);
            XContentBuilder source = sourceSupplier.get();