Remove some non-oslo projects from oslo.json

Neither cliff nor requirements are oslo projects. We shouldn't track
them as part of Oslo since Oslo cores don't have +2 on them.

Change-Id: Iebd8cc506482760f40f6dcbc13fb5b5e9c2a683a

projects/oslo.json

@@ -5,7 +5,6 @@
         "openstack-dev/hacking",
         "openstack-dev/oslo-cookiecutter",
         "openstack-dev/pbr",
-        "openstack/cliff",
         "openstack/oslo-incubator",
         "openstack/oslo-specs",
         "openstack/oslo.config",
@@ -19,8 +18,7 @@
         "openstack/oslotest",
         "openstack/pycadf",
         "openstack/stevedore",
-        "openstack/taskflow",
-        "openstack/requirements"
+        "openstack/taskflow"
     ],
     "core-team-gerrit-group": "oslo-core"
 }