Revert "Ensure rest_route valid for plain permalink requests."

This reverts commit 1e546ed.

includes/classes/ExternalConnections/WordPressExternalConnection.php

@@ -809,13 +809,7 @@ public function check_connections() {
 			'endpoint_suggestion' => false,
 		);
 
-		$remote_request_url = untrailingslashit( $this->base_url );
-		if ( str_ends_with( $remote_request_url, '?rest_route=' ) ) {
-			// It's a request to get the REST API index using plain permalinks and needs a trailing slash.
-			$remote_request_url = user_trailingslashit( $remote_request_url );
-		}
-
-		$response = Utils\remote_http_request( $remote_request_url, $this->auth_handler->format_get_args( array( 'timeout' => self::$timeout ) ) );
+		$response = Utils\remote_http_request( untrailingslashit( $this->base_url ), $this->auth_handler->format_get_args( array( 'timeout' => self::$timeout ) ) );
 
 		$body = wp_remote_retrieve_body( $response );