Investigate Import/Export excessive memory consumption issues

We received several reports on customer being unable to export projects:

• https://gitlab.com/gitlab-com/dev-sub-department/section-dev-request-for-help/-/issues/112+
• https://gitlab.com/gitlab-com/dev-sub-department/section-dev-request-for-help/-/issues/122+
• https://gitlab.com/gitlab-com/dev-sub-department/section-dev-request-for-help/-/issues/125+

From what we've seen, exports started to not complete due to excessive memory consumption starting in GitLab 16.0.4. Prior to that, customers have been able to successfully export projects.

We investigate this further by trying to reproduce the problem in two runs/migrations (before 16.0.4 and after).