[omnibox]: Remove OmniboxGroupSuggestionsBySearchVsUrl from fieldtrial_testing_config

Followup to making the feature default enabled.

Bug: 966462
Change-Id: Ic7924049df1e14373c0a695878d51d32d0d77ff1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724118Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Mark Pearson <mpearson@chromium.org>
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682267}

testing/variations/fieldtrial_testing_config.json

@@ -3533,7 +3533,6 @@
                     "enable_features": [
                         "OmniboxDisplayTitleForCurrentUrl",
                         "OmniboxDocumentProvider",
-                        "OmniboxGroupSuggestionsBySearchVsUrl",
                         "OmniboxLocalEntitySuggestions",
                         "OmniboxRichEntitySuggestions",
                         "OmniboxTailSuggestions",