Revert "core: Prevent StopVm to interleave with other VM locked actions"

This reverts commit 37411acc82c03ba8e3150e5d9b4aad2e6d39a414.

in retrospective there is a much simpler and less intrusive solution[1]
and it was noted this fix will cause restoreStatless to fail sense it will fail to take the vm lock on destory

[1] the replacement fix - 42bdcd9

Change-Id: I0c12f4e2855e9ddfb6d696167b20352914825a9a
Signed-off-by: Roy Golan <rgolan@redhat.com>