Creating custom disk does not work as expected
CLOUDSTACK-6603 [Upgrade]DB Exception while Autoscale monitoring after upgrading from 4.3 to 4.4

(cherry picked from commit c282bb3a1293fbbfdb306263ea52464862670fb3)
(cherry picked from commit fc7d0b2a333e510619f14528a72e35bbf9ed7045)
CLOUDSTACK-6172: Adding new test case to verify this fix

Conflicts:

	test/integration/component/test_volumes.py

Signed-off-by: sanjeev <sanjeev@apache.org>

CLOUDSTACK-6172: Fixed review comments provided in RR 25771
Test to verify fix for issue "Exception when attaching data disk to RHEL vm on vSphere

Added Rhel6 template details to test_data.py

Signed-off-by: sanjeev <sanjeev@apache.org>

Fixed review comments provided in RR 25536