Bump default docker test image

Updates the default redislabs/client-libs-test docker tag used by tests (a single shared config in @redis/test-utils), adjusts the CI matrix, commits on a freshly-reset bump-test-image branch, force-pushes it, and opens (or updates) a PR against redis/node-redis master.

Inputs

• tag (required): the new docker tag, e.g. 8.8.0, 8.8-rc1, custom-28772936538-debian, unstable-24425681442-debian. If given as redislabs/client-libs-test:<tag>, strip the image name.
• version (sometimes required): the Redis version the tag represents, e.g. 8.10.
  • Derivable when the tag is version-shaped: 8.8.0 → 8.8, 8.8-rc1 → 8.8, 8.8-m03 → 8.8.
  • NOT derivable for custom-* / unstable-* tags — if missing, ask the user which Redis version the tag maps to before doing anything else.

If no tag was given at all, ask for it and stop.

Step 1 — Sync master from upstream

Remotes: upstream = redis/node-redis (canonical), origin = the user's fork.