Fix deprecated redis values used in tests

What does this MR do?

Fix deprecated redis values used in tests

The values:
- `global.redis.password`, and
- `global.redis.<instance>.password`
are deprecated in favor of:
- `global.redis.auth`, and
- `global.redis.<instance>.auth`.

Test cases that used the deprecated values caused multiple warnings to be
during test execution.

Relates chart docs: https://docs.gitlab.com/charts/installation/upgrade.html#use-of-globalredispassword

Checklist

See Definition of done.

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

Test Plan

Compare the logs of a slow_unit_tests jobs on master (e.g., https://gitlab.com/gitlab-org/cloud-native/gitlab-operator/-/jobs/4803457312) with the logs the latest job ran for this MR.

There should be no more logs like:

warning: destination for gitlab.redis.global.redis.password is a table. Ignoring non-table value ()

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
• When ready for review, MR is labeled "~workflow::ready for review" per the Distribution MR workflow

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 omnibus-gitlab opened
• Validate potential values for new configuration settings. Formats such as integer 10, duration 10s, URI scheme://user:passwd@host:port may require quotation or other special handling when rendered in a template and written to a configuration file.

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