Editor: revert add grid layout type

Reverting the previous commit because it causes e2e to fail on trunk.

See #58554.


git-svn-id: https://develop.svn.wordpress.org/trunk@55958 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-theme-json.php

@@ -1370,7 +1370,7 @@ class WP_Theme_JSON {
 
 				if (
 					! empty( $class_name ) &&
-					is_array( $base_style_rules )
+					! empty( $base_style_rules )
 				) {
 					// Output display mode. This requires special handling as `display` is not exposed in `safe_style_css_filter`.
 					if (