Add AggregateMetricDouble/Block to misc. tests in ES|QL

[limotova]

AggregateMetricDouble and its Block is missing from a few tests

In org.elasticsearch.compute.data:

• AggregateMetricDoubleBlockEqualityTests (only null equality is tested)
• BasicBlockTests
• BasicPageTests
• BlockAccountingTests
• BlockBuilderCopyFromTests
• BlockBuilderTests
• BlockFactoryTests
• BlockSerializationTests
• BlockValueAsserter
• CompositeBlockTests (possibly; needs investigation)
• FilteredBlockTests

org.elasticsearch.compute.operator.topn:

• TopNEncoderTests

org.elasticsearch.compute.test:

• BlockTestUtils (add to randomValue and append and see where it takes us)
• RandomBlock (add to randomBlock and randomElementType and see where it takes us)

org.elasticsearch.xpack.esql.analysis:

• AnalyzerTests (test implicit casting of aggregate metric double using CSV dataset)

[elasticsearchmachine]

Pinging @elastic/es-storage-engine (Team:StorageEngine)