remove unicode literal from code
remove unicode literal from code

All strings are considered as unicode string from Python 3.

This patch drops the explicit unicode literal (u'...')
appearances from the unicode strings.

Change-Id: I408f0615d84f956a9ad98134cedd3390012c17eb
Co-Authored-By: LiZekun <12319a490d3a24c9363e138db0845865f3f9d61f@qq.com>

openstack/puppet-gnocchi,openstack/puppet-gnocchi