Multisite: Display registered new_item text for post post type in My Sites menu.

Previously, the My Sites menu would show "New Post" even if the `post` post type labels had been filtered to different values.

Props nahuelmahe.
Fixes #44794.


git-svn-id: https://develop.svn.wordpress.org/trunk@43590 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/admin-bar.php

@@ -613,7 +613,7 @@ function wp_admin_bar_my_sites_menu( $wp_admin_bar ) {
 				array(
 					'parent' => $menu_id,
 					'id'     => $menu_id . '-n',
-					'title'  => __( 'New Post' ),
+					'title'  => get_post_type_object( 'post' )->labels->new_item,
 					'href'   => admin_url( 'post-new.php' ),
 				)
 			);