Avoid calling external API when migrating within the same GitLab instance

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

The following discussion from !52330 (merged) should be addressed:

• @reprazent started a discussion: (+1 comment)

  This is a really cool use for GraphQL @georgekoltsov, I like the way it's done 😄. I had one thought on the things @kassio already brought up in !52330 (comment 496545172). But as said, that's not for here.

  Another thing I was wondering: If we're importing from one group into another, on the same instance, I assume this is also possible? In those cases, we could theoretically avoid calling the API (and occupying a puma worker), but instead execute the query directly in the sidekiq-worker by calling GitlabSchema.execute there. Is that something worth exploring?