gitlab: Port to the new lister api
No evolution, plain portage.
Note: The existing missing tests, eventual paper cuts, and authentication support will be addressed in subsequent diffs:
- D4930: pagination test
- !391 (closed): incremental lister test
- !181 (closed): rate limit test
- !332 (closed): Support authentication
Related to #2987 (closed)
Test Plan
tox
Migrated from D4929 (view on Phabricator)