Mount /dev/vdc in /var/lib/jenkins on isotester1

Originally created by @bertagaz on #10158 (Redmine)

With a 4GB filesystem, as the other isotesters. This one has been left untouched for the test suite team to be able to test on lizard. See tails/sysadmin#9645 for the rationale.

Parent Task: tails/sysadmin#5288