Handle explicit empty database batches

[trask]

Summary

Core behavioral changes from #19019, reflecting clarification in open-telemetry/semantic-conventions#3811.

This updates shared DB semconv handling so explicit empty batches (db.operation.batch.size = 0) are treated as batches for stable span names and db.query.summary.

[Copilot]

Pull request overview

This PR updates shared DB semconv handling to treat explicit empty batches (db.operation.batch.size = 0) as batches for stable span names and db.query.summary. Previously, only batchSize > 1 was considered a batch; now any non-null, non-one value triggers batch behavior. The PR also extends MultiQuery to track per-query operation names and collection names for the singleOperationAndCollection feature.

Changes:

• Updated batch condition from batchSize > 1 to batchSize != 1 consistently across DbClientAttributesExtractor, SqlClientAttributesExtractor, and DbClientSpanNameExtractor.
• Extended MultiQuery with operationName/collectionName fields and emitted them in the multi-query path when singleOperationAndCollection is enabled.
• Added comprehensive test coverage for empty batch (batchSize=0) scenarios and the multi-query singleOperationAndCollection behavior.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
DbClientAttributesExtractor.java	Updated batch condition to batchSize != 1; renamed intermediate variable to emitBatchSize for clarity.
SqlClientAttributesExtractor.java	Same batch condition update; added DB_OPERATION_NAME/DB_COLLECTION_NAME emission from MultiQuery in multi-query path.
DbClientSpanNameExtractor.java	Updated isBatch() method to treat size 0 as batch; added early "BATCH" return for empty query texts in batch context.
MultiQuery.java	Added operationName/collectionName fields, builder tracking via UniqueValue, and "BATCH"-prefixed construction in build().
SqlClientAttributesExtractorTest.java	Added tests for empty batch attributes and multi-query batch with singleOperationAndCollection.
DbClientSpanNameExtractorTest.java	Added tests for empty batch span names and default mock setup for batch size.

[trask]

Closing, going to focus on getting the test-only improvements in first, then come back and add this so we can see effect on tests at the same time.