GitLab Workspaces Proxy - Ensure OAuth redirects to GitLab work on HTTP and HTTPS both
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### Tasks
- [ ] Test if we are able to perform oauth redirect when gitlab is on HTTPS. If we fail, quick solution is to use `InsecureSkipVerify` TLS config and create a followup issue for better resolution.
- More details at https://gitlab.com/gitlab-org/gitlab/-/issues/407152+
- [ ] Once we have ensure TLS support, please update the developer docs in gitlab-workspaces-proxy to use `https://gdk.test:3443` post this and ensure everyone on the team uses it.
### Testing
Add relevant feature specs
issue