For #17799: Add extensions submenu item.

app/src/androidTest/java/org/mozilla/fenix/ui/robots/ThreeDotMenuMainRobot.kt

@@ -411,8 +411,7 @@ private fun assertSettingsButton() = settingsButton()
     .check(matches(withEffectiveVisibility(Visibility.VISIBLE)))
     .check(matches(isCompletelyDisplayed()))
 
-private val addOnsText = if (FeatureFlags.toolbarMenuFeature) "Extensions" else "Add-ons"
-private fun addOnsButton() = onView(allOf(withText(addOnsText)))
+private fun addOnsButton() = onView(allOf(withText("Add-ons")))
 private fun assertAddOnsButton() {
     onView(withId(R.id.mozac_browser_menu_menuView)).perform(swipeDown())
     addOnsButton().check(matches(withEffectiveVisibility(Visibility.VISIBLE)))

app/src/main/java/org/mozilla/fenix/components/toolbar/DefaultToolbarMenu.kt

@@ -399,13 +399,9 @@ class DefaultToolbarMenu(
             onItemTapped.invoke(ToolbarMenu.Item.Downloads)
         }
 
-        val extensionsItem = BrowserMenuImageText(
-            context.getString(R.string.browser_menu_extensions),
-            R.drawable.ic_addons_extensions,
-            primaryTextColor()
-        ) {
-            onItemTapped.invoke(ToolbarMenu.Item.AddonsManager)
-        }
+        val extensionsItem = WebExtensionPlaceholderMenuItem(
+            id = WebExtensionPlaceholderMenuItem.MAIN_EXTENSIONS_MENU_ID
+        )
 
         val syncedTabs = BrowserMenuImageText(
             label = context.getString(R.string.synced_tabs),