Navi: Remove NuxOnboarding from testing config.

Bug: 993611
Change-Id: I58a9e4ed71bdbd29663f24942f6e00bfe5068532
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1764565
Auto-Submit: Hector Carmona <hcarmona@chromium.org>
Commit-Queue: Steven Holte <holte@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Cr-Commit-Position: refs/heads/master@{#692154}

testing/variations/fieldtrial_testing_config.json

@@ -3525,26 +3525,6 @@
             ]
         }
     ],
-    "NaviOnboarding": [
-        {
-            "platforms": [
-                "windows"
-            ],
-            "experiments": [
-                {
-                    "name": "AppsBackground-007",
-                    "params": {
-                        "new-user-modules": "nux-google-apps,nux-ntp-background,nux-set-as-default,signin-view",
-                        "onboarding-group": "AppsBackgroundSynthetic-007",
-                        "returning-user-modules": "nux-set-as-default"
-                    },
-                    "enable_features": [
-                        "NuxOnboarding"
-                    ]
-                }
-            ]
-        }
-    ],
     "NavigationPredictor": [
         {
             "platforms": [