Rename "service_unittests" -> "services_unittests".

testing/buildbot/chromium.android.json

 {
   "Android Cronet Builder": {
     "additional_compile_targets": [
       "cronet_package"
     ]
   },
   "Android N5X Swarm Builder": {
     "gtest_tests": [
       {
         "args": [
@@ skipping 1164 matching lines @@
             {
               "link": [
                 "https://luci-logdog.appspot.com/v/?s",
                 "=android%2Fswarming%2Flogcats%2F",
                 "${TASK_ID}%2F%2B%2Funified_logcats"
               ],
               "name": "shard #${SHARD_INDEX} logcats"
             }
           ]
         },
-        "test": "service_unittests"
+        "test": "services_unittests"
       },
       {
         "merge": {
           "args": [
             "--bucket",
             "chromium-result-details",
             "--test-name",
             "sql_unittests"
           ],
           "script": "//build/android/pylib/results/presentation/test_results_presentation.py"
@@ skipping 3683 matching lines @@
       },
       {
         "test": "content_shell_test_apk"
       },
       {
         "test": "webview_instrumentation_test_apk"
       }
     ]
   }
 }