Apex: limits verify per node to 1

This will limit how many simultaneous builds we can do at a time on
build server, but will stop the bug we are hitting where deploy (next
job) and functest (current job) start at the same time by blocking
parent jobs.

Change-Id: If23ce857d7ef043c408b0eb6a74357ce1278e4b9
Signed-off-by: Tim Rozet <trozet@redhat.com>