Revert "include admins::mortals on osmium, to allow MediaWiki deployments"

Already there...

This reverts commit 84f88847d230613583d73f6f56bf1862c40490fd.

Change-Id: Ia3cce30c8289e95cb54c24dd9b079cfeee0eb613
Merge "Revert "include admins::mortals on osmium, to allow MediaWiki deployments"" into production