Update certificates for Workspaces and Update Documentation

Update on Dec 3, 2024 From the recent instructions for cert renewal https://gitlab.com/gitlab-org/workspaces/gitlab-workspaces-proxy/-/blob/main/README.md?ref_type=heads - The certs are created using mkcert, which has longer expiry, so the current certificates expire on 3 March 2027

New Rotating cerdentials hanbook page - https://internal.gitlab.com/handbook/engineering/infrastructure/engineering-productivity/rotating-credentials/#workspaces_domain_cert

Handbook update 4- https://gitlab.com/gitlab-com/content-sites/internal-handbook/-/merge_requests/5845

The Certificates used for Workspaces proxy needs to be updated every 90 days. The current one expires on 2024-02-20.

Also update the documentation on the expiry date of new keys in https://gitlab.com/gitlab-org/quality/engineering-productivity/team/-/blob/main/runbooks/rotating-credentials.md#workspaces_domain_cert

Edited by Nivetha Prabakaran