Revert "Run browser_tests as a 25% experiment on Mac10.13 Tests & mac_chromium_rel_ng."

This reverts commit b20ba21c.

Reason for revert: Added capacity isn't finding bot deaths as fast as manual, targeted swarming invocations. Will reland this after having some confidence that the 10.13 bot-killer tests are identified.

Original change's description:
> Run browser_tests as a 25% experiment on Mac10.13 Tests & mac_chromium_rel_ng.
> 
> Bug: 828031
> Change-Id: I1d4bdb235ad9d93df0653215c7c5928c471b6c16
> Reviewed-on: https://chromium-review.googlesource.com/c/1277693
> Reviewed-by: Robert Sesek <rsesek@chromium.org>
> Commit-Queue: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#599364}

TBR=rsesek@chromium.org,jbudorick@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 828031
Change-Id: I38c447f53d533eeff40abfd462c3bb1f09eac75f
Reviewed-on: https://chromium-review.googlesource.com/c/1282283Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Robert Sesek <rsesek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599869}

testing/buildbot/chromium.mac.json

@@ -3645,25 +3645,6 @@
         },
         "test": "boringssl_ssl_tests"
       },
-      {
-        "args": [
-          "--test-launcher-filter-file=../../testing/buildbot/filters/mac_window_server_killers.browser_tests.filter",
-          "--gtest_shuffle"
-        ],
-        "experiment_percentage": 25,
-        "swarming": {
-          "can_use_on_swarming_builders": true,
-          "dimension_sets": [
-            {
-              "gpu": "none",
-              "os": "Mac-10.13",
-              "pool": "Chrome-quarantine"
-            }
-          ],
-          "shards": 10
-        },
-        "test": "browser_tests"
-      },
       {
         "args": [
           "--enable-features=WebUIPolymer2",

testing/buildbot/test_suite_exceptions.pyl

@@ -75,6 +75,7 @@
       'mac-views-rel', # https://crbug.com/828031
       # chromium.mac
       'Mac10.10 Tests', # https://crbug.com/828031
+      'Mac10.13 Tests', # https://crbug.com/828031
       # chromium.memory
       'Linux TSan Tests',  # https://crbug.com/368525
       'Mac ASan 64 Tests (1)', # https://crbug.com/828031
@@ -132,23 +133,6 @@
           ],
         },
       },
-      'Mac10.13 Tests': {
-        # A subset of tests seem to cause WindowServer deaths on VMs.
-        # crbug.com/828031 et al.
-        'args': [
-          '--test-launcher-filter-file=../../testing/buildbot/filters/mac_window_server_killers.browser_tests.filter',
-          '--gtest_shuffle',
-        ],
-        'experiment_percentage': 25,
-        'swarming': {
-          'dimension_sets': [
-            {
-              'pool': 'Chrome-quarantine',
-              'gpu': 'none',
-            },
-          ],
-        },
-      },
       'Mac10.13 Tests (dbg)': {
         # A subset of tests seem to cause WindowServer deaths on VMs.
         # crbug.com/828031 et al.