Remove common.transport.wsgi.utils

This module is just being used by v1_[01]/pools.py and contains 2
functions that are common *just* for the wsgi transport. Since we
already have a wsgi.utils modules, it's not worth to keep this one in
common.

Change-Id: I8374e2bf62e1b87f7e60a3dd68bec196bc57948d
Merge "Remove common.transport.wsgi.utils"