Fix case of item extras in browser_menu_action event (#19487)

* Fix case of item extras in browser_menu_action event

Update the event description to match the values observed in telemetry.

* Line length

app/metrics.yaml

@@ -205,11 +205,13 @@ events:
         description: |
           A string containing the name of the item the user tapped. These items
           include:
-
-            Settings, Help, Desktop Site toggle on/off, Find in Page,
-            New Tab, Private Tab, Share, Report Site Issue, Back/Forward button,
-            Reload Button, Quit, Reader Mode On, Reader Mode Off, Open In app,
-            Add To Top Sites, Add-ons Manager, Bookmarks, History
+          add_to_homescreen, add_to_top_sites, addons_manager, back, bookmark,
+          bookmarks, desktop_view_off, desktop_view_on, downloads,
+          find_in_page, forward, help, history, library, new_private_tab,
+          new_tab, open_in_app, open_in_fenix, quit, reader_mode_appearance,
+          reader_mode_off, reader_mode_on, reload, save_to_collection,
+          set_default_browser, settings, share, stop, sync_account, and
+          sync_tabs.
     bugs:
       - https://github.com/mozilla-mobile/fenix/issues/1024
     data_reviews: