chore: content_script_version_2: add simple protection and rename mes…

…sages_backup if exists (#2531)

migrations/message_store_postgres/content_script_version_2.nim

@@ -1,4 +1,5 @@
 const ContentScriptVersion_2* = """
+ALTER TABLE IF EXISTS messages_backup RENAME TO messages;
 ALTER TABLE messages RENAME TO messages_backup;
 ALTER TABLE messages_backup DROP CONSTRAINT messageIndex;