Fix Google Memorystore support for Action Cable

What does this MR do?

This adds the nil id to cable.yml when redis_enable_client is set to false.

This also enables support for redis_enable_client for the individual redis configs when configuring separate instances.

Note that this does not actually fix the bug until gitlab!75173 (merged) is also merged.

Action Cable was enabled by default in 14.5 so this affects all instances using GCP Memorystore that upgrade to 14.5

Related issues

Related to gitlab#346421 (closed)

Checklist

See Definition of done.

For anything in this list which will not be completed, please provide a reason in the MR discussion

Required

• Merge Request Title, and Description are up to date, accurate, and descriptive
• MR targeting the appropriate branch
• MR has a green pipeline on GitLab.com
• Pipeline is green on dev.gitlab.org if the change is touching anything besides documentation or internal cookbooks
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Expected (please provide an explanation if not completing)

• Test plan indicating conditions for success has been posted and passes
• Documentation created/updated
• Tests added
• Integration tests added to GitLab QA
• Equivalent MR/issue for the GitLab Chart opened