Remove DelayNavigation from fieldtrial_testing_config

The experiment is over and this could mask real improvements on the
critical loading path, especially CPU performance wins on the IO thread.

Bug: None
Change-Id: I904e1be21961aca3e35245f569651700f1b0dad8
Reviewed-on: https://chromium-review.googlesource.com/822298Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#523530}

testing/variations/fieldtrial_testing_config.json

@@ -1166,30 +1166,6 @@
             ]
         }
     ],
-    "DelayNavigation": [
-        {
-            "platforms": [
-                "android",
-                "chromeos",
-                "linux",
-                "mac",
-                "win"
-            ],
-            "experiments": [
-                {
-                    "name": "DelayNavigation",
-                    "params": {
-                        "delay_millis": "4",
-                        "delay_probability": "0.5",
-                        "randomize_delay": "true"
-                    },
-                    "enable_features": [
-                        "DelayNavigation"
-                    ]
-                }
-            ]
-        }
-    ],
     "DesktopIOSPromotion": [
         {
             "platforms": [