Remove warning from gitlab-ctl geo promote and add deprecation warnings to legacy commands

Summary

As part of the rollout for our single promotion command gitlab-ctl geo promote, we need to:

• Remove the production readiness warning from gitlab-ctl geo promote
• Display deprecation and removal warning messages when gitlab-ctl promote-to-primary-node and gitlab-ctl promote-db are run. The message should read something like: As of GitLab 14.5, this command is deprecated in favor of gitlab-ctl geo promote. This command will be removed in GitLab 15.0. Please see <documentation link> for more details.