Reenable telemetry_perf_unittests on android-marshmallow-arm64-rel.

Tbr: crouleau@chromium.org,nednguyen@google.com,perezju@chromium.org
Bug: 903849
Change-Id: Ib0857c3bbd630ea7e47928dcd43b9f9fcc12597e
Reviewed-on: https://chromium-review.googlesource.com/c/1335935Reviewed-by: John Budorick <jbudorick@chromium.org>
Reviewed-by: Ned Nguyen <nednguyen@google.com>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608015}

testing/buildbot/chromium.android.json

@@ -23138,7 +23138,6 @@
           "--browser=android-chromium",
           "--device=android"
         ],
-        "experiment_percentage": 100,
         "isolate_name": "telemetry_perf_unittests",
         "name": "telemetry_perf_unittests",
         "swarming": {

testing/buildbot/test_suite_exceptions.pyl

@@ -1020,7 +1020,6 @@
           ],
           'shards': 15,
         },
-        'experiment_percentage': 100, # https://crbug.com/903849
       },
       # chromium.android.fyi
       'x86 Cloud Tester': {