Block canvas: clean up templates (#6620)

* Clean up templates supplied.

* Remove customTemplates.

* Add blank and modify customTemplates definition.

block-canvas/templates/footer-only.html

@@ -1,3 +0,0 @@
-<!-- wp:post-content {"layout":{"inherit":true},"lock":{"move":false,"remove":true}} /-->
-
-<!-- wp:template-part {"slug":"footer","tagName":"footer"} /-->

block-canvas/templates/header-footer-only.html

@@ -1,10 +0,0 @@
-<!-- wp:template-part {"slug":"header","tagName":"header"} /-->
-
-<!-- wp:group {"tagName":"main","lock":{"move":false,"remove":true}} -->
-<main class="wp-block-group">
-
-<!-- wp:post-content {"layout":{"inherit":true},"lock":{"move":false,"remove":true}} /-->
-</main>
-<!-- /wp:group -->
-
-<!-- wp:template-part {"slug":"footer","tagName":"footer"} /-->

block-canvas/templates/page.html

@@ -1,4 +1,3 @@
-
 <!-- wp:template-part {"slug":"header","tagName":"header"} /-->
 
 <!-- wp:group {"layout":{"inherit":true}} -->

block-canvas/theme.json

@@ -9,22 +9,6 @@
                 "post"
             ],
             "title": "Blank"
-        },
-        {
-            "name": "header-footer-only",
-            "postTypes": [
-                "page",
-                "post"
-            ],
-            "title": "Header and Footer Only"
-        },
-        {
-            "name": "footer-only",
-            "postTypes": [
-                "page",
-                "post"
-            ],
-            "title": "Footer Only"
         }
     ],
     "settings": {