fix(migrations): change deleteEmptyConversations to run only once

Author: nsarrazin

src/lib/migrations/routines/09-delete-empty-conversations.ts

@@ -81,7 +81,7 @@ const deleteEmptyConversations: Migration = {
 		await deleteConversations(collections);
 		return true;
 	},
-	runEveryTime: true,
+	runEveryTime: false,
 	runForHuggingChat: "only",
 };