Bug 1946868 - Remove "Turn on/off Vertical Tabs" in the tab context menu r=sidebar-reviewers,tabbrowser-reviewers,nsharpley,dao

Backout of Bug 1944016 - Add new strings to tab context menu for switching to/from vertical tabs.

Differential Revision: https://phabricator.services.mozilla.com/D238106

browser/components/tabbrowser/content/tabbrowser.js

@@ -8498,17 +8498,6 @@ var TabContextMenu = {
         : "close-tabs-to-the-end"
     );
 
-    // Update context menu item for "Turn (on/off) Vertical Tabs".
-    const toggleVerticalTabsItem = document.getElementById(
-      "context_toggleVerticalTabs"
-    );
-    document.l10n.setAttributes(
-      toggleVerticalTabsItem,
-      gBrowser.tabContainer?.verticalMode
-        ? "tab-context-disable-vertical-tabs"
-        : "tab-context-enable-vertical-tabs"
-    );
-
     // Disable "Close Tabs to the Left/Right" if there are no tabs
     // preceding/following it.
     let noTabsToStart = !gBrowser._getTabsToTheStartFrom(this.contextTab)