Move some EE project routes under /-/ scope

What does this MR do?

This MR does next:

• Combine 2 /-/ scopes into one in ee/config/routes/project.rb. Move /-/ scope to the top of the file. Same as CE.
• Move autocomplete_sources and operations EE-only routes for consistency with CE routes.

Legacy redirects are already covered by CE code https://gitlab.com/gitlab-org/gitlab-ce/blob/44f53d46234ae5263fad4320d8dc3308b0801891/config/routes/project.rb#L512-513

Related issues:

• https://gitlab.com/gitlab-org/gitlab-ce/issues/61985
• https://gitlab.com/gitlab-org/gitlab-ce/issues/26407

Previous merge requests:

• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28435
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28717
• https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28830

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• 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