Since Linaro shut down their nodepool provider - OpenDev infra
is left with OSUOSL cloud with max 15 instances running - let's
not put any additional strain on CI (especially that it seems
there are some I/O or similar issues that cause our jobs to
time out).
Change-Id: I7f0f723b37e552c4ea01bf51b6354209608d904a
fd4f1a8a82