Fix use of wrong storage pools for NetApp Drivers

Fix use of wrong storage pools for NetApp Drivers

When using NetApp drivers, all available flexvols on
a datastore are being reported to the Cinder Scheduler
as available storage pools. This allows Cinder volumes
to be created on flexvols not designated for OpenStack.

This commit fixes the problem by delimiting which pools are
eligible for provisioning via a configuration parameter
'netapp_pool_name_search_pattern'. This allows
the Cinder drivers to operate against a restricted
set of storage containers.

DocImpact
Co-Authored-By: Rushil Chugh <rushil@netapp.com>
Co-Authored-By: Michael Price <michael.price@netapp.com>
Closes-Bug: #1493399
Change-Id: I7b6f2205470ecbbcb165889db19e1168117dd0b2