test: skip live storage migration on CentOS 7 (#7862)

since #7570, The detail 'Host.OS' of centos7 host is changed from 'CentOS' to 'CentOS Linux'

Author: weizhouapache

test/integration/smoke/test_vm_life_cycle.py

@@ -1556,7 +1556,7 @@ def setUp(self):
             self.skipTest("Requires at least two hosts for performing migration related tests")
 
         for host in self.hosts:
-            if host.details['Host.OS'] in ['CentOS']:
+            if host.details['Host.OS'] and host.details['Host.OS'].startswith('CentOS'):
                 self.skipTest("live migration is not stabily supported on CentOS")
 
     def tearDown(self):