Revert of Enable SequencedWorkerPool to TaskScheduler redirection in testing config.

testing/variations/fieldtrial_testing_config.json

 {
     "AndroidSessionNotifications": [
         {
             "platforms": [
                 "android"
             ],
             "experiments": [
                 {
                     "name": "Disabled"
                 }
@@ skipping 176 matching lines @@
             "platforms": [
                 "android",
                 "chromeos",
                 "ios",
                 "linux",
                 "mac",
                 "win"
             ],
             "experiments": [
                 {
-                    "name": "Enabled",
-                    "params": {
-                        "Background": "3;8;0.1;0;30000",
-                        "BackgroundFileIO": "3;8;0.1;0;30000",
-                        "Foreground": "8;32;0.3;0;30000",
-                        "ForegroundFileIO": "8;32;0.3;0;30000",
-                        "RedirectSequencedWorkerPools": "true"
-                    }
+                    "name": "Default"
                 },
                 {
                     "name": "EnableViaFlag",
                     "forcing_flag": "enable-browser-task-scheduler",
                     "params": {
                         "Background": "3;8;0.1;0;30000",
                         "BackgroundFileIO": "3;8;0.1;0;30000",
                         "Foreground": "8;32;0.3;0;30000",
                         "ForegroundFileIO": "8;32;0.3;0;30000",
                         "RedirectSequencedWorkerPools": "true"
@@ skipping 2028 matching lines @@
                 {
                     "name": "Enabled",
                     "enable_features": [
                         "use-new-media-cache"
                     ]
                 }
             ]
         }
     ]
 }