The SQL queries and memory allocation in MergeRequests::RefreshService
is dominated by queries for Project and Route loads. On staging, the
absence of an inverse relationship caused Rails to make over 1100
extraneous SQL queries for the www-gitlab-com repository.
Relates to https://gitlab.com/gitlab-org/gitlab-ce/issues/49703
Just like with the GitHub importer, the Bitbucket Server importer can hit the
default 60 s idle-in-transaction timeouts if it takes too long to create the
merge request. We solve this by using the same approach as the GitHub importer:
1. Bypass all validation and hooks in creating a merge request
2. Insert the Git data in a separate transaction
Part of #50021
