The following aggregation tests all contain switch statements with branches that will never execute. The tests use a `between(x, y)` switch expression, but there are `case` values that are outside the randomised range. We need to fix these before #88739 can be merged. By "fix", I mean either remove the spurious cases, or if we actually want them, then extend the randomized range.

   * InternalAutoDateHistogramTests
   * InternalAvgTests
   * InternalDerivativeTests
   * InternalGeoCentroidTests
   * InternalWeightedAvgTests
   * SignificantLongTermsTests
   * SignificantStringTermsTests
server/src/test/java/org/elasticsearch/search/aggregations/bucket/terms/SignificantStringTermsTests.java
metadata,
            format,
            subsetSize,
            supersetSize,
            significanceHeuristic,
            buckets
        );
    }
    @Override
    protected Class<ParsedSignificantStringTerms> implementationClass() {
        return ParsedSignificantStringTerms.class;
    }
    @Override
    protected InternalSignificantTerms<?, ?> mutateInstance(InternalSignificantTerms<?, ?> instance) {
        if (instance instanceof SignificantStringTerms stringTerms) {
            String name = stringTerms.getName();
            int requiredSize = stringTerms.requiredSize;
            long minDocCount = stringTerms.minDocCount;
            DocValueFormat format = stringTerms.format;
            long subsetSize = stringTerms.getSubsetSize();
            long supersetSize = stringTerms.getSupersetSize();
            List<SignificantStringTerms.Bucket> buckets = stringTerms.getBuckets();
            SignificanceHeuristic significanceHeuristic = stringTerms.significanceHeuristic;
            Map<String, Object> metadata = stringTerms.getMetadata();
            switch (between(0, 5)) {
                case 0 -> name += randomAlphaOfLength(5);
                case 1 -> requiredSize += between(1, 100);
                case 2 -> minDocCount += between(1, 100);
                case 3 -> subsetSize += between(1, 100);
                case 4 -> supersetSize += between(1, 100);