Remove duplicated mapping key in config/locales/en.yml

The "errors" section was defined twice in this file, the first one was
the once being removed here, another one is at line 164 (before removal)
or line 158 (after removal).

The content of duplicated strings definition are totally the same, the
second part has more data (41 lines in total, compare to the removed 6
lines), so I removed the first part but not the second part.

cc !16710

changelogs/unreleased/FixLocaleEN.yml

+---
+title: Remove duplicated mapping key in config/locales/en.yml
+merge_request: 30980
+author: Peter Dave Hello
+type: fixed

config/locales/en.yml

@@ -16,12 +16,6 @@ en:
         api_url: "Sentry API URL"
       project/metrics_setting:
         external_dashboard_url: "External dashboard URL"
-  errors:
-    messages:
-      label_already_exists_at_group_level: "already exists at group level for %{group}. Please choose another one."
-      wrong_size: "is the wrong size (should be %{file_size})"
-      size_too_small: "is too small (should be at least %{file_size})"
-      size_too_big: "is too big (should be at most %{file_size})"
   views:
     pagination:
       previous: "Prev"