Clean up unified limits configuration for nova and glance

This is a followup for change Ifdef3510bc7da3098a71739814e35dbaf612ae34
which added configuration of unified limits for nova. This removes an
unnecessary wrapper unsetting of OS_ env variables, unnecessary quoting
on an iniset config value, and a hardcoding of user domain. The glance
code from which the nova code was originally copied is also cleaned up.

Change-Id: I4921af5cc0f624dd5aa848533f7049ee816be593
2 files changed