Remove DownloadRename entry from field trial testing config.

The server-side config shows that this has launched.

Bug: 1126640
Change-Id: Ib27ab13a1f6bd4365be76900c768bf451a8ed406
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2632186Reviewed-by: Hesen Zhang <hesen@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#843951}

testing/variations/fieldtrial_testing_config.json

@@ -2697,21 +2697,6 @@
             ]
         }
     ],
-    "DownloadRename": [
-        {
-            "platforms": [
-                "android"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "DownloadRename"
-                    ]
-                }
-            ]
-        }
-    ],
     "DownloadResumptionWithoutStrongValidators": [
         {
             "platforms": [