fix(kafka): resolve memory refs per action container

[weicao]

Problem

Fresh task54 backup runtime on exact addon 2067c105 created an action Pod with only backupdata and manager containers. Both failed with container kafka not found because four Kafka ComponentDefinitions hard-coded resourceFieldRef.containerName: kafka for KB_KAFKA_CONTAINER_MEMORY_LIMIT_MIB.

Change

• remove the hard-coded container name from the four Kafka ComponentDefinitions so Kubernetes resolves limits.memory against the container executing the action
• add a structured Helm-render regression test that requires exactly the four Kafka definitions to expose the memory env with resource=limits.memory, divisor=1Mi, and no container override

Verification

• focused TDD: 1 failing example before the template change, then 1/0
• full Kafka ShellSpec with Bash 5.3: 31/0
• Bash 3.2 runnable subset: 9/0
• sh -n, Ruby syntax, ShellCheck, and git diff --check: pass

Stacked on #3248 exact addon head; kept Draft because the base is a custom branch.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 25 lines in your changes missing coverage. Please review.
✅ Project coverage is 0.00%. Comparing base (2067c10) to head (2bf7ece).

Files with missing lines	Patch %	Lines
...kafka/scripts-ut-spec/container_memory_ref_spec.sh	0.00%	25 Missing ⚠️

Additional details and impacted files

@@                  Coverage Diff                  @@
##           audrey/task55-heap-40   #3249   +/-   ##
=====================================================
  Coverage                   0.00%   0.00%           
=====================================================
  Files                         76      77    +1     
  Lines                       9426    9451   +25     
=====================================================
- Misses                      9426    9451   +25     

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