Feature support Valkey

[mayrstefan]

General information

Because of a former license change some linux distributions migrate from redis to its fork valkey (e.g. SLES 15 SP7 does not contain redis anymore. It was replaced with valkey). Same as the MySQL plugin also supports its fork MariaDB the redis plugin should support Valkey.
mk_redis already works with Valkey if configured explicitly and either redis-cli is present or is a symlink to valkey-cli.

Proposed changes

Use the mk_redis plugin to detect valkey-server instances and auto-detect the available cli.

This requires two modifications:

1. detect running instances with binaries named valkey-server
2. make use of the valkey-cli if available

As a bonus this PR moves the special case for the redis-cli of a CheckMK site also into the redis_args function. So configuration of REDIS_CLI_COMMAND is all in one place.

[github-actions]

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[martinhv]

At dev, I would consider creating a dedicated valkey plug-in:

• Eventually users will forget the relation valkey = fork of redis. So they will be looking for valkey, not redis
• Changes in valkey will impact the redis agent plug-in visa versa (example: 7ed5059)
• Makes automated testing more difficult