Revert "Always mount a /run tmpfs in the container"

This reverts commit 905795ece624675abe2ec2622b0bbafdb9d7f44c.

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Merge pull request #5975 from tianon/revert-run-tmpfs

Revert "Always mount a /run tmpfs in the container"