The script was embedded in the playbook, which leads to some
pain with regard to editing and reviewing as well as manual
testing.
The disadvantage of doing this is that it can make jobs
somewhat less portable between projects, but in this case
that's not really an issue.
There are further improvements that can made to remove duplication
between the nested and non-nested versions of these jobs. This
change will make it easier for those changes to be made as
people have time.
Change-Id: Ia6795ef15a03429c19e66ed6d297f62da72cc052