Remove ViewsBrowserWindows from fieldtrial_testing_config.json

No code checks for this feature or experiment anymore.

BUG=876090

Change-Id: I3b190857043ea067e28842458d2343a08c9d3920
Reviewed-on: https://chromium-review.googlesource.com/c/1255893Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Robert Kaplow (sloooow) <rkaplow@chromium.org>
Commit-Queue: Robert Liao <robliao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596353}

testing/variations/fieldtrial_testing_config.json

@@ -5036,21 +5036,6 @@
             ]
         }
     ],
-    "ViewsBrowserWindows": [
-        {
-            "platforms": [
-                "mac"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled_20180703",
-                    "enable_features": [
-                        "ViewsBrowserWindows"
-                    ]
-                }
-            ]
-        }
-    ],
     "VizDisplayCompositor": [
         {
             "platforms": [