Make the number of reusable blocks returned from the API unlimited

This is to fix WordPress#26352. Having no limit seems like it could be risky, but
there are a number of other places in the codebase where all entities
are returned in one call to the API, including categories, which could
return a similar amount of data to this.

packages/editor/src/components/provider/index.js

@@ -323,7 +323,8 @@ export default compose( [
 			selectionEnd: getEditorSelectionEnd(),
 			reusableBlocks: select( 'core' ).getEntityRecords(
 				'postType',
-				'wp_block'
+				'wp_block',
+				{ 'per_page': -1 }
 			),
 			hasUploadPermissions: defaultTo(
 				canUser( 'create', 'media' ),