Posts: Prevent an empty excerpt when groups and nested column blocks are present.

This improves the logic within `excerpt_remove_blocks()` to better handle `innerBlocks`. This prevents an empty excerpt from being returned when `core/columns`, `core/column`, and `core/group` blocks are present.

This issue has been surfaced in the Query Loop block, where excerpts can be set to display. 

Props aristath.
Fixes #53604.

git-svn-id: https://develop.svn.wordpress.org/trunk@51348 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/deprecated.php

@@ -4207,3 +4207,20 @@ function wp_sensitive_page_meta() {
 	<?php
 	wp_strict_cross_origin_referrer();
 }
+
+/**
+ * Render inner blocks from the `core/columns` block for generating an excerpt.
+ *
+ * @since 5.2.0
+ * @deprecated 5.8.0
+ *
+ * @access private
+ *
+ * @param array $columns        The parsed columns block.
+ * @param array $allowed_blocks The list of allowed inner blocks.
+ * @return string The rendered inner blocks.
+ */
+function _excerpt_render_inner_columns_blocks( $columns, $allowed_blocks ) {
+	_deprecated_function( __FUNCTION__, '5.8.0', '_excerpt_render_inner_blocks()' );
+	return _excerpt_render_inner_blocks( $columns, $allowed_blocks );
+}