Restyle status message input on profile settings (EE-port)

EE-port of https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20903

What does this MR do?

Restyle the input field for setting a user status. Also removes the corresponding feature flag and makes it generally available.

Screenshots

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
  • will happen in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/21045
• Tests added for this feature/bug
• Conforms to the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer

What are the relevant issue numbers?

closes https://gitlab.com/gitlab-org/gitlab-ce/issues/49645