Primary key for pool in catalogue table is unreasonable

Based on current implement of sqlalchemy driver, we're setting
primary key for pool, but unfortunately, it's incorrect, because
user will definately put many queues for one pool. This fix will
remove the primary key for pool and imporve the unit test to
cover it.

Closes-Bug: 1338907

Change-Id: I20b4176e96760356dfd23211d7170c074db8254b
Merge "Primary key for pool in catalogue table is unreasonable"