Improve Capacity filter logging
Improve Capacity filter logging

Logging in scheduler's filters have improved greatly over the years, but
there are still two code paths that exclude backends but don't log the
reason.

This patch adds debug log levels to those 2 paths so all exclusion code
paths will be covered.

TrivialFix

Change-Id: I57c773849200439713b18b61874dc33d8ee34390

Datera/cinder,eharney/cinder,j-griffith/cinder,openstack/cinder,eharney/cinder,openstack/cinder,mahak/cinder,j-griffith/cinder,phenoxim/cinder,mahak/cinder,Datera/cinder,phenoxim/cinder