Remove legacy-tempest-dsvm-full-drbd-devstack job

https://review.openstack.org/#/c/629061/ deprecated the DRBD driver with
the introduction of their newer Linstor driver. Since this is now marked
as unsupported, we can drop running CI against the old driver.

Change-Id: I088e20583d5ae7c565cd0651786d71afcb2e1c67
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

.zuul.yaml

@@ -113,22 +113,6 @@
               - ^setup.cfg$
               - ^tools/.*$
               - ^tox.ini$
-        - legacy-tempest-dsvm-full-drbd-devstack:
-            voting: false
-            irrelevant-files:
-              - ^(test-|)requirements.txt$
-              - ^.*\.rst$
-              - ^api-ref/.*$
-              - ^cinder/hacking/.*$
-              - ^cinder/locale/.*$
-              - ^cinder/tests/functional.*$
-              - ^cinder/tests/unit.*$
-              - ^contrib/block-box.*$
-              - ^doc/.*$
-              - ^releasenotes/.*$
-              - ^setup.cfg$
-              - ^tools/.*$
-              - ^tox.ini$
         - legacy-tempest-dsvm-full-devstack-plugin-nfs:
             voting: false
             irrelevant-files: