Tag Cloud: Improve state of block with no tags (WordPress#63774)

* Render nothing when no tags are available in tag cloud block

* Added condition to display placeholder in editor

* Fix phpcs errors

* Use wp_is_serving_rest_request function for conditional check

Co-authored-by: akasunil <sunil25393@git.wordpress.org>
Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: richtabor <richtabor@git.wordpress.org>

packages/block-library/src/tag-cloud/index.php

@@ -29,8 +29,13 @@ function render_block_core_tag_cloud( $attributes ) {
 	);
 	$tag_cloud = wp_tag_cloud( $args );
 
-	if ( ! $tag_cloud ) {
-		$tag_cloud = __( 'There’s no content to show here yet.' );
+	if ( empty( $tag_cloud ) ) {
+		// Display placeholder content when there are no tags only in editor.
+		if ( wp_is_serving_rest_request() ) {
+			$tag_cloud = __( 'There’s no content to show here yet.' );
+		} else {
+			return '';
+		}
 	}
 
 	$wrapper_attributes = get_block_wrapper_attributes();