refactor: gitlab adopts new remote api helper

[klesh]

Summary

refactor: Gitlab adopts new remote API helper

Feature #5914 has been reverted:

• The list remote scopes API won't include projects under other user's account
• You may still add them by using the search remote scope
  Because:
• No Gitlab API can be utilized elegantly for the purpose, the current implementation uses the /projects API which also returns many other unneeded entries that need to be dropped which is inefficiency and may cause significant delay on the config-ui when the total number of projects is huge.
• The implementation is too complicated to understand
• The deduplication from the current implementation was flawed
• The use-case of "adding projects under another user's name" is rare, it is not worth the trouble. Search and add is good enough

Does this close any open issues?

Part of #5519

Screenshots