CLOUDSTACK-4257: Additional asserts for storage migration test
CLOUDSTACK-4257: Additional asserts for storage migration test

Test whether valid storage pools are listed and at least one pool is
available for migration.

Signed-off-by: Prasanna Santhanam <82219615980488abd2acc1a3d71cfb58f0b2b8b6@apache.org>

mufaddalq/cloudstack-datera-driver,mufaddalq/cloudstack-datera-driver,mufaddalq/cloudstack-datera-driver,mufaddalq/cloudstack-datera-driver,mufaddalq/cloudstack-datera-driver,mufaddalq/cloudstack-datera-driver