Convert cacheinvalidation_unittests to run exclusively on Swarming

testing/buildbot/chromium.chromiumos.json

Index: testing/buildbot/chromium.chromiumos.json
diff --git a/testing/buildbot/chromium.chromiumos.json b/testing/buildbot/chromium.chromiumos.json
index 7dc4ff804b2cc4a81c230f55a3ed2920978e926b..c966bc6721951cbcca04933a8a36b811bf7c0e3a 100644
--- a/testing/buildbot/chromium.chromiumos.json
+++ b/testing/buildbot/chromium.chromiumos.json
@@ -152,6 +152,9 @@
         "test": "base_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "cacheinvalidation_unittests"
       },
       {
@@ -387,6 +390,9 @@
         "test": "browser_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "cacheinvalidation_unittests"
       },
       {
@@ -620,6 +626,9 @@
         "test": "browser_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "cacheinvalidation_unittests"
       },
       {