Improve SSH key expiration warning emails

Merged Dan Jensen requested to merge 322637-improve-ssh-key-expiration-warning-emails into master

What does this MR do?

Previously the emails sent about SSH key expiration (introduced in %13.11) did not explain that expired SSH keys will no longer be usable in GitLab 14.0. That is critical information, because without it even users who receive a warning email might still be surprised when their SSH key stops being usable. This adds that information to the emails so users cannot be surprised by the change in SSH behavior after upgrading to GitLab 14.0.

This problem was noted by @mwoolf while working on a related MR. This language will be updated under #331928 (closed) in %14.0.

Does this MR meet the acceptance criteria?

Conformity

Availability and Testing

Security

Does this MR contain changes to processing or storing of credentials or tokens, authorization and authentication methods or other items described in the security review guidelines? If not, then delete this Security section.

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team

Related to #322637 (closed)

Edited by Dan Jensen