Move profiles/keys#get_keys to users#ssh_keys

What does this MR do?

Moves profiles/keys#get_keys to users#ssh_keys with keeping SSH Keys of the user publicly accessible.

In %13.2, once !35507 (merged) moved profiles/keys#get_keys to users#ssh_keys on Web UI, but it changed the behavior for non-logged in users, in %13.4 !42288 (merged) reverted that to keep the feature publicly accessible.

security & ~"technical debt": All Profiles::*Controllers are designed only for operations the logged-in and own user. Having skip_before_action :authenticate_user! to some action there can potentially be a security hole.

Screenshots (strongly suggested)

n/a

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Related to #288950 (closed)