Revert of Fix typo in Android perf variations for unified media pipeline...

Revert of Fix typo in Android perf variations for unified media pipeline trial. (patchset #1 id:1 of https://codereview.chromium.org/1808803002/ )

Reason for revert:
This is breaking the media tests downstream.

Original issue's description:
> Fix typo in Android perf variations for unified media pipeline trial.
>
> BUG=533190
> TEST=none
>
> Committed: https://crrev.com/31d22b6338ac6ac8b95e9f4c20cdccea11609be2
> Cr-Commit-Position: refs/heads/master@{#381498}

TBR=asvitkine@chromium.org,dalecurtis@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=533190

Review URL: https://codereview.chromium.org/1813553002

Cr-Commit-Position: refs/heads/master@{#381585}

testing/variations/fieldtrial_testing_config_android.json

@@ -381,7 +381,7 @@
             }
         }
     ],
-    "UnifiedMediaPipelineTrial": [
+    "UnifiedMediaPipeline": [
         {
             "group_name": "Enabled"
         }