Remove ProbingScreenshareBwe entry from the testing config.

Bug: 1126640, 763949, webrtc:10509
Change-Id: I7e586fe8f2dcb6de4cb29aafbb5490aa9835953b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485299Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Commit-Queue: Caitlin Fischer <caitlinfischer@google.com>
Cr-Commit-Position: refs/heads/master@{#818975}

testing/variations/fieldtrial_testing_config.json

@@ -7810,21 +7810,6 @@
             ]
         }
     ],
-    "WebRTC-ProbingScreenshareBwe": [
-        {
-            "platforms": [
-                "windows",
-                "mac",
-                "chromeos",
-                "linux"
-            ],
-            "experiments": [
-                {
-                    "name": "1.0,2875,80,40,-60,3"
-                }
-            ]
-        }
-    ],
     "WebRTC-SendSideBwe-WithOverhead": [
         {
             "platforms": [