Upgrade the mail_room gem to version 0.10.0
Summary
Currently GitLab.com is missing structured logging coming from the mailroom service. With the recent release of version 0.10.0 of this gem, we should now have the capability to better control logging coming from this service.
https://github.com/tpitale/mail_room/releases
Possible fixes
GitLab will need an upgrade on: https://gitlab.com/gitlab-org/gitlab/blob/master/Gemfile#L414
Omnibus will need to have additional options added such that Administrators of GitLab can configure the logging as desired: https://gitlab.com/gitlab-org/omnibus-gitlab
And the same bit of configuration should be made available to charts: https://gitlab.com/gitlab-org/charts/gitlab
Note: this is a follow-on issue to #30070 (closed)