Blockbase: Remove custom 404 templates (#5332)

skatepark/block-templates/404.html

@@ -1,14 +0,0 @@
-<!-- wp:template-part {"slug":"header","tagName":"header"} /-->
-
-<!-- wp:spacer {"height":170} -->
-<div style="height:170px" aria-hidden="true" class="wp-block-spacer"></div>
-<!-- /wp:spacer -->
-
-<!-- wp:group {"tagName":"main","layout":{"inherit":true}} -->
-<main class="wp-block-group">
-	<!-- wp:pattern {"slug":"blockbase/404"} /-->
-	<!-- wp:search {"label":""} /-->
-</main>
-<!-- /wp:group -->
-
-<!-- wp:template-part {"slug":"footer","tagName":"footer","className":"site-footer-container"} /-->