Workaround for grenade jobs to read CIRROS_VERSION variable from
stackrc.
We also give the possibility to specify a custom CIRROS_VERSION
In addition, fix transient iDRAC WS-Man BIOS test.
Depends-On: https://review.opendev.org/c/openstack/ironic/+/786387
Change-Id: Ic7f5dae5e6aa6916f0a7d73f43cc9552349385c5