Remove a couple Media entries from the testing config.

The server-side configs show that these studies have launched.

Bug: 1126640
Change-Id: I29f802ad203fecc0eab77f68df169e11d02099c0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2631433Reviewed-by: Becca Hughes <beccahughes@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#844115}

testing/variations/fieldtrial_testing_config.json

@@ -4153,24 +4153,6 @@
             ]
         }
     ],
-    "MediaFeeds": [
-        {
-            "platforms": [
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "MediaFeeds"
-                    ]
-                }
-            ]
-        }
-    ],
     "MediaFoundationAsyncH264Encoding": [
         {
             "platforms": [
@@ -4201,25 +4183,6 @@
             ]
         }
     ],
-    "MediaHistory": [
-        {
-            "platforms": [
-                "android",
-                "chromeos",
-                "linux",
-                "mac",
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "UseMediaHistoryStore"
-                    ]
-                }
-            ]
-        }
-    ],
     "MediaLearningSmoothnessExperiment": [
         {
             "platforms": [