Remove the need to use health check token by adding ability to whitelist hosts

Deprecate healthcheck access token in favor of ip whitelist.

Healthcheck access token was used to protect access to monitoring resources /-/readiness /-/liveness /-/metrics and /healthcheck/

Initially I wanted to remove support for token completely but after reading existing documentation e.g. about being able to connect it to Pingdom. I decided its better to follow some deprecation policy where it will be still available maybe even until next major release, or maybe at least just a few next releases.

So to bring back token support I just remove I've added its implementation to RequiresWhitelistedMonitoringClient. Which is now not the best named class.

Why was this MR needed?

in #33949 (closed) we decided that instead of token an ip whitelist will be more versatile, and easier to manage in omnibus etc.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #33949 (closed)