feat: ignore unavailable users (#9406)

docs/usage/configuration-options.md

lib/config/definitions.ts

lib/config/types.ts

lib/platform/gitlab/__snapshots__/index.spec.ts.snap

lib/platform/gitlab/http.ts

lib/platform/gitlab/index.spec.ts

lib/platform/gitlab/index.ts

lib/platform/gitlab/types.ts

lib/platform/types.ts

lib/workers/pr/__snapshots__/index.spec.ts.snap

lib/workers/pr/index.spec.ts

lib/workers/pr/index.ts

lib/workers/repository/init/index.spec.ts

lib/workers/repository/init/index.ts