Add tempest.api.compute.servers.test_servers_negative to skiplist

Test is failing in master

Change-Id: I7fff4895f61f24a1ee1d0361fa42081a73caf8c5
Related-Bug: #1892837

roles/validate-tempest/vars/tempest_skip.yml

@@ -87,6 +87,13 @@ known_failures:
         reason: 'RBAC policy resource conflict'
         lp: 'https://bugs.launchpad.net/tripleo/+bug/1753209'
     jobs: []
+  - test: 'tempest.api.compute.servers.test_servers_negative.ServersNegativeTestJSON'
+    deployment: 'overcloud'
+    releases:
+      - name: 'master'
+        reason: 'Nova Bug'
+        lp: 'https://bugs.launchpad.net/tripleo/+bug/1892837'
+    jobs: []
   - test: 'tempest.api.volume.test_volumes_snapshots.VolumesSnapshotTestJSON.test_volume_from_snapshot_no_size'
     deployment: 'overcloud'
     releases:
@@ -1349,4 +1356,4 @@ known_failures:
       - name: 'ussuri'
         reason: 'No valid host was found. Reason: No conductor service registered which supports driver fake-hardware for conductor group'
         lp: 'https://bugs.launchpad.net/tripleo/+bug/1890424'
-    jobs: []
+    jobs: []