Move display_service_unittests to services_unittests.

testing/buildbot/chromium.chromiumos.json

 {
   "Linux ChromiumOS Builder": {
     "additional_compile_targets": [
       "All"
     ]
   },
   "Linux ChromiumOS Ozone Tests (1)": {
     "gtest_tests": [
       {
         "swarming": {
@@ skipping 128 matching lines @@
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "device_unittests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
-        "test": "display_service_unittests"
-      },
-      {
-        "swarming": {
-          "can_use_on_swarming_builders": true
-        },
         "test": "display_unittests"
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "events_unittests"
       },
       {
         "swarming": {
@@ skipping 1012 matching lines @@
       },
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "wm_unittests"
       }
     ]
   }
 }