Remove some studies from the config.

This is because Windows has a command line size limit and too many
testing configs can result in the limit being hit.

See comment 1 on the bug for details on why these studies are candidates
for removal.

Bug: 1126640

Change-Id: Ib3c5b2fdc5917bdf6a4119ff35657c1c29082bd8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2402108Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#810059}

testing/variations/fieldtrial_testing_config.json

@@ -4512,21 +4512,6 @@
             ]
         }
     ],
-    "NativeNotifications": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "NativeNotifications"
-                    ]
-                }
-            ]
-        }
-    ],
     "NativeWindowOcclusionTrackerWin": [
         {
             "platforms": [
@@ -4598,21 +4583,6 @@
             ]
         }
     ],
-    "NetworkServiceSandbox": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "NetworkServiceSandbox"
-                    ]
-                }
-            ]
-        }
-    ],
     "NewTabInProductHelp": [
         {
             "platforms": [
@@ -5492,23 +5462,6 @@
             ]
         }
     ],
-    "PermissionPromptUIViews": [
-        {
-            "platforms": [
-                "chromeos",
-                "linux",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "BlockPromptsEnabled",
-                    "enable_features": [
-                        "BlockPromptsIfDismissedOften"
-                    ]
-                }
-            ]
-        }
-    ],
     "PersistentHistograms": [
         {
             "platforms": [
@@ -5626,26 +5579,6 @@
             ]
         }
     ],
-    "PreloadMetadataLazyLoad": [
-        {
-            "platforms": [
-                "android",
-                "android_weblayer",
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "PreloadMetadataLazyLoad"
-                    ]
-                }
-            ]
-        }
-    ],
     "PrivacyElevatedAndroid": [
         {
             "platforms": [