Add Redisson batch size attribute

[trask]

Summary

• emit db.operation.batch.size for Redisson CommandsData pipeline spans in stable DB semantic convention mode
• exclude the MULTI transaction wrapper command from batch-size counting
• add stable-mode pipeline assertions and document why current MULTI wrapper spans omit batch size

Testing

• git diff --check -- instrumentation/redisson/redisson-common-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/common/v3_0/RedissonDbAttributesGetter.java instrumentation/redisson/redisson-common-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/common/v3_0/RedissonRequest.java instrumentation/redisson/redisson-common-3.0/testing/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/AbstractRedissonAsyncClientTest.java instrumentation/redisson/redisson-common-3.0/testing/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/AbstractRedissonClientTest.java
• ./gradlew :instrumentation:redisson:redisson-common-3.0:javaagent:spotlessCheck :instrumentation:redisson:redisson-common-3.0:testing:spotlessCheck :instrumentation:redisson:redisson-3.0:javaagent:compileTestJava :instrumentation:redisson:redisson-3.17:javaagent:compileTestJava

[Copilot]

Pull request overview

This PR adds support for emitting the stable DB semantic convention attribute db.operation.batch.size on Redisson pipeline (CommandsData) spans, while ensuring the MULTI transaction wrapper command is excluded from batch-size counting.

Changes:

• Add batch-size computation on RedissonRequest for CommandsData and expose it via the DB attributes getter.
• Emit db.operation.batch.size only when it represents a true batch (>1 user operations), excluding MULTI from the count.
• Extend Redisson client/async client tests to assert db.operation.batch.size in stable semconv mode and document why MULTI wrapper spans omit it.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
instrumentation/redisson/redisson-common-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/common/v3_0/RedissonRequest.java	Computes batch size for CommandsData requests and excludes MULTI wrapper from the count.
instrumentation/redisson/redisson-common-3.0/javaagent/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/common/v3_0/RedissonDbAttributesGetter.java	Exposes the computed batch size through DbClientAttributesGetter.
instrumentation/redisson/redisson-common-3.0/testing/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/AbstractRedissonClientTest.java	Adds stable-mode assertions for db.operation.batch.size on pipeline spans and documents MULTI wrapper behavior.
instrumentation/redisson/redisson-common-3.0/testing/src/main/java/io/opentelemetry/javaagent/instrumentation/redisson/AbstractRedissonAsyncClientTest.java	Documents MULTI wrapper span omission rationale in async atomic batch test coverage.