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/metrics/InternalAvgTests.java
break;
            case 1:
                if (Double.isFinite(sum)) {
                    sum += between(1, 100);
                } else {
                    sum = between(1, 100);
                }
                break;
            case 2:
                if (Double.isFinite(count)) {
                    count += between(1, 100);
                } else {
                    count = between(1, 100);
                }
                break;
            case 3:
                if (metadata == null) {
                    metadata = Maps.newMapWithExpectedSize(1);
                } else {
                    metadata = new HashMap<>(instance.getMetadata());
                }
                metadata.put(randomAlphaOfLength(15), randomInt());
                break;
            default:
                throw new AssertionError("Illegal randomisation branch");
        }
        return new InternalAvg(name, sum, count, formatter, metadata);
    }
}