Since we merged the change to have partition and wholedisk
testing on basic_ops most of the jobs started requiring 2 VMs
to run the tempest tets.
Let's increase on the ironic-base so all jobs will be default to 2.
Removing IRONIC_VM_COUNT=2 from jobs that uses ironic-base as parent.
Change-Id: I13da6275c04ffc6237a7f2edf25c03b4ddee936a