Revert "Add fieldtrial testing config for ButterForPasswords"

This reverts commit 8e4ad533.

Reason for revert: crbug.com/1136758 test failures on macOS

Original change's description:
> Add fieldtrial testing config for ButterForPasswords
>
> Bug: 991510
> Change-Id: I447e99f11c322478f007557ab268823ed2616042
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2455446
> Commit-Queue: Jesse Doherty <jwd@chromium.org>
> Auto-Submit: Marc Treib <treib@chromium.org>
> Reviewed-by: Jesse Doherty <jwd@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#815355}

TBR=jwd@chromium.org,treib@chromium.org

Change-Id: I41a6d02cb9dce80e5bc41e087c53f8b6b5be0335
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 991510
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2462884Reviewed-by: Hajime Hoshi <hajimehoshi@chromium.org>
Commit-Queue: Hajime Hoshi <hajimehoshi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815507}

testing/variations/fieldtrial_testing_config.json

@@ -1262,29 +1262,6 @@
             ]
         }
     ],
-    "ButterForPasswords": [
-        {
-            "platforms": [
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "ButterForPasswords",
-                    "params": {
-                        "event_1": "name:passwords_account_storage_unselected;comparator:==0;window:180;storage:180",
-                        "event_trigger": "name:passwords_account_storage_trigger;comparator:<5;window:180;storage:180",
-                        "event_used": "name:passwords_account_storage_used;comparator:==0;window:180;storage:180"
-                    },
-                    "enable_features": [
-                        "EnablePasswordsAccountStorage",
-                        "IPH_PasswordsAccountStorage"
-                    ]
-                }
-            ]
-        }
-    ],
     "CSSMatchedPropertiesCacheDependencies": [
         {
             "platforms": [