Ensure logrotate is on by default for gitaly/*.log

What does this MR do?

While working on gitlab-com/gl-infra/scalability#519 (closed) I noticed that the default logrotate config in Omnibus ignores /var/log/gitlab/gitaly/*.log even though Gitaly writes some non-Runit logs there. (gitaly!2678 (merged) adds a new log file to that directory.)

This change adds gitaly to the default logrotate services.

Related issues

gitlab-com/gl-infra/scalability#519 (closed)

Checklist

See Definition of done.

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I am not 100% sure how logs are handled in CNG but I can see that the default application logs go to a file and that script is written so that it works correctly if there is more than one log file. So adding one more log file to Gitaly in CNG should not break anything.