Revert "disable voting on gate-tempest-dsvm-virtual-ironic"

Now that the transitive dependency between ironic, oslo-test, and the
rest of the world has been resolved by patch
15eaf5f933f9bc8654cc808074366b7d981fc7b4, we should allow the
gate-tempest-dsvm-virtual-ironic job to resume voting.

This reverts commit 6810a8b8a846af6e078ed4d8f7773c77a51f9194.

Change-Id: I84085311d6f35440e5eadf8389173273273b0356
Merge "Revert "disable voting on gate-tempest-dsvm-virtual-ironic""