Merge branch 'rodrigo/increase-spread-workers-github-import' into 'master'

Increase number of concurrent import workers in GitHub Import

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/137832



Merged-by: George Koltsov <gkoltsov@gitlab.com>
Approved-by: Bojan Marjanovic <bmarjanovic@gitlab.com>
Approved-by: George Koltsov <gkoltsov@gitlab.com>
Reviewed-by: Bojan Marjanovic <bmarjanovic@gitlab.com>
Co-authored-by: Rodrigo Tomonari <rtomonari@gitlab.com>