OOR-CORS: update fieldtrial_testing_config to match

Now that our default finch parameter does not contain
the workaround for the YouTube, let's remove it from
the fieldtrial_testing_config so that it matches the
distributed default configuration.

Bug: 1001450
Change-Id: I332b336e3d5567f81766758ec861ad0a3a0bbd82
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2065781
Auto-Submit: Takashi Toyoshima <toyoshim@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Takashi Toyoshima <toyoshim@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743429}

testing/variations/fieldtrial_testing_config.json

@@ -4013,8 +4013,8 @@
                 {
                     "name": "Enabled",
                     "params": {
-                        "extra-safelisted-request-headers": "x-googapps-allowed-domains,youtube-restrict",
-                        "extra-safelisted-request-headers-for-enterprise": "x-googapps-allowed-domains,youtube-restrict"
+                        "extra-safelisted-request-headers": "x-googapps-allowed-domains",
+                        "extra-safelisted-request-headers-for-enterprise": "x-googapps-allowed-domains"
                     },
                     "enable_features": [
                         "OutOfBlinkCors"