tests: Fix intermittent failure in ovs-monitor-ipsec test.

tests: Fix intermittent failure in ovs-monitor-ipsec test.

The ovs-monitor-ipsec test waits for a specific number of lines
of output before doing a comparison to the correct values.  However,
some copy and pasted code did not update the number of lines to
look for resulting in a race condition where the comparison could
happen before the script finished running.