Compute global configuration only once

Ticket:	#4929
(cherry picked from commit 35c1e28488018061bba4b3fe6480dff2f5ff87b2)
Use actual tag value for portal instead of unicode repr

Ticket:	#4929
(cherry picked from commit e771822a41cb87c94f81f3f9472f333e4dd06e51)
Remove unused iSCSI models import

Ticket:	#4929
(cherry picked from commit 4cc1578c2d39be59302e16adf3ebe5fd916847ab)