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/histogram/InternalAutoDateHistogramTests.java
protected InternalAutoDateHistogram createTestInstance(
        String name,
        Map<String, Object> metadata,
        InternalAggregations aggregations,
        long startingDate,
        RoundingInfo[] roundingInfos,
        int roundingIndex,
        DocValueFormat format
    ) {
        int nbBuckets = randomNumberOfBuckets();
        int targetBuckets = randomIntBetween(1, nbBuckets * 2 + 1);
        List<InternalAutoDateHistogram.Bucket> buckets = new ArrayList<>(nbBuckets);
        long interval = randomIntBetween(1, 3);
        long intervalMillis = roundingInfos[roundingIndex].roughEstimateDurationMillis * interval;
        for (int i = 0; i < nbBuckets; i++) {
            long key = startingDate + (intervalMillis * i);
            buckets.add(i, new InternalAutoDateHistogram.Bucket(key, randomIntBetween(1, 100), format, aggregations));
        }
        BucketInfo bucketInfo = new BucketInfo(roundingInfos, roundingIndex, InternalAggregations.EMPTY);
        return new InternalAutoDateHistogram(name, buckets, targetBuckets, bucketInfo, format, metadata, randomNonNegativeLong());
    }
    @Override
    protected boolean supportsSampling() {
        return true;
    }
    @Override
    protected InternalAutoDateHistogram createTestInstance(String name, Map<String, Object> metadata, InternalAggregations aggregations) {
        RoundingInfo[] roundingInfos = AutoDateHistogramAggregationBuilder.buildRoundings(null, null);
        int roundingIndex = between(0, roundingInfos.length - 1);