Export commit notes as a separate relation

When exporting CI pipeline notes, N+1 queries are executed for each pipeline as there is no association between pipeline notes and pipelines. And because the association doesn't exist, we can't preloading the notes.

It turns out that CI pipeline notes under the hood are notes made on commits (Note - noteably_type: commit), so in practice, we don't need to export the notes as part of the CI pipeline relation and commit notes can be exported separately.

Proposed solution

• Export commit notes as a separate relation
• Implement a solution that is compatible with previously exported files
• Implement a pipeline in Gitlab Direct transfer to import commit notes