[Java SDK] Add Async-Specific Tests for Consumer Groups Operations #2225

Title

Add comprehensive async tests for ConsumerGroupsTcpClient

Description

The async client's ConsumerGroupsTcpClient lacks dedicated async-specific tests. While the blocking client has consumer group tests, the async implementation needs its own test coverage to ensure proper handling of CompletableFuture-based operations.

Tasks

• Create AsyncConsumerGroupsTest.java with tests for:
  • Create consumer group async
  • Delete consumer group async
  • Join consumer group async
  • Leave consumer group async
  • Get consumer group details async
  • List all consumer groups async
• Test error scenarios:
  • Invalid group ID
  • Non-existent group
  • Concurrent join/leave operations
• Verify proper CompletableFuture exception handling

Labels

enhancement, testing, async-client, java-sdk