CA-148243: Getting rid of bad assertion failures during VM lifecycle
operations

Issue: After a VM lifecycle operation, assert statement throws assertion
failure in an ugly manner.

Fix: Removing the assert statements and replacing them with
vm_bad_power_state error in case the power state of VM doesn't match the
expected state after some lifecycle operation.

Signed-off-by: Ravi Pandey <ravi.pandey@citrix.com>
Adding a function check_power_state
Signed-off-by: Ravi Pandey <ravi.pandey@citrix.com>
Merge pull request #1976 from ravippandey/CA-148243_tr3

CA-148243: Getting rid of bad assertion failure after VM starts