Remove Show109ObsoleteInfobar from field trial testing config.

The feature seems to no longer appear in the code.

Bug: 1126640
Change-Id: Ifcdc7966cf366470c18028a8d078d2f7716789f0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2427132Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#810271}

testing/variations/fieldtrial_testing_config.json

@@ -6482,21 +6482,6 @@
             ]
         }
     ],
-    "Show109ObsoleteInfobar": [
-        {
-            "platforms": [
-                "mac"
-            ],
-            "experiments": [
-                {
-                    "name": "Enabled",
-                    "enable_features": [
-                        "Show109ObsoleteInfobar"
-                    ]
-                }
-            ]
-        }
-    ],
     "SimplifiedUrlDisplay": [
         {
             "platforms": [