Remove dupe of content_browsertests from Marshmallow 64 bit tester.

TBR=jbudorick@chromium.org, stip@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2347713002
Cr-Commit-Position: refs/heads/master@{#419041}

testing/buildbot/chromium.android.json

@@ -3582,37 +3582,6 @@
         },
         "test": "content_unittests"
       },
-      {
-        "override_isolate_target": "content_browsertests",
-        "swarming": {
-          "can_use_on_swarming_builders": true,
-          "cipd_packages": [
-            {
-              "cipd_package": "infra/tools/luci/logdog/butler/${platform}",
-              "location": "bin",
-              "revision": "git_revision:3ff24775a900b675866fbcacf2a8f98a18b2a16a"
-            }
-          ],
-          "dimension_sets": [
-            {
-              "device_os": "MMB29Q",
-              "device_type": "bullhead"
-            }
-          ],
-          "hard_timeout": 960,
-          "output_links": [
-            {
-              "link": [
-                "https://luci-logdog.appspot.com/v/?s",
-                "=android%2Fswarming%2Flogcats%2F",
-                "${TASK_ID}%2F%2B%2Funified_logcats"
-              ],
-              "name": "shard #${SHARD_INDEX} logcats"
-            }
-          ]
-        },
-        "test": "content_browsertests"
-      },
       {
         "override_isolate_target": "device_unittests",
         "swarming": {