Add redis-cluster-6.2.12 image for CI pipeline

What does this MR do and why?

This MR introduces a new image redis-cluster-6.2.12 to be used in the pipeline changes in gitlab!120566 (merged).

The Dockerfile and script are simplified versions of the image used in the MR (https://hub.docker.com/r/grokzen/redis-cluster). It adds extra logic on top of the official redis:6.2.12 image (https://hub.docker.com/layers/library/redis/6.2.12/images/sha256-ffe23b67a0f93865b9c83eba3ec0740991af09ea8c74962d5095c21265432d5f?context=explore).

Closes #127 (closed)

Local testing

1. Build and run the image:

docker build  -f Dockerfile.redis-cluster-6.2.12 -t redis-cluster-ci .
docker run  -p 7001-7003:7001-7003 redis-cluster-ci # the redis server start-up + cluster formation logs lines will show up

2. Check cluster state from outside the docker container using redis-cli

redis-cli -p 7001 cluster nodes
a8eb234786cc4ab3650a035cb3630baf619a4090 127.0.0.1:7002@17002 master - 0 1684469004396 2 connected 5461-10922
4c31ed4fbfcf8ef9bf44b58bff2721b2b5f27a10 127.0.0.1:7003@17003 master - 0 1684469004905 3 connected 10923-16383
05faeaf34884aa5ad7aee203561c0e7cbd36c124 127.0.0.1:7001@17001 myself,master - 0 1684469002000 1 connected 0-5460

Checklist

• (If applicable) Add patches if required for upgrading Ruby version in https://gitlab.com/gitlab-org/gitlab-build-images/-/tree/master/patches/ruby.