fix local emoji detection

https://github.com/misskey-dev/misskey/pull/7526#discussion_r641886612

src/misc/populate-emojis.ts

@@ -61,7 +61,7 @@ export async function populateEmoji(emojiName: string, noteUserHost: string | nu
 
 	if (emoji == null) return null;
 
-	const isLocal = emojiName.endsWith('@.');
+	const isLocal = emoji.host == null;
 	const url = isLocal ? emoji.url : `${config.url}/proxy/image.png?${query({url: emoji.url})}`;
 
 	return {