Geo: Fix SSH push proxy

What does this MR do?

Fixes SSH push Proxy for Geo secondary node.

In https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/9502 I added JWT scope enforcement but I overlooked that SSH push proxy feature also uses JWT token. Thus it got broken. To generate scope in Gitlab::Geo::GitPushSSHProxy I would need to query the database to get project id from repository full path which is suboptimal. So I decided to use repository full path as a scope itself. It fixes this problem as well as makes code easier and more effective. However, we previously decided that we don't want to generate scope and to enforce it in the same release for the sake of a smooth update, so I reverted the scope enforcement for repositories in 11.9 and will schedule it for 11.10 again.

Closes https://gitlab.com/gitlab-org/quality/nightly/issues/78

Closes https://gitlab.com/gitlab-org/quality/nightly/issues/77

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?
• Security reports checked/validated by reviewer