Add test cases which check that when a XoT primary server is
unreachable or is already marked as unreachble then the next
primary server in the list is used.
(cherry picked from commit 12225d125b)
Add test cases which check that when a XoT primary server is
unreachable or is already marked as unreachble then the next
primary server in the list is used.
(cherry picked from commit 12225d125b)