Fix State Sync CTAS Replace (#861)

* switch state sync to replace_query from ctas replace

* change back to ctas but drop table first

Author: eakmanrq

sqlmesh/core/state_sync/engine_adapter.py

@@ -437,9 +437,12 @@ def _backup_state(self) -> None:
             self.seeds_table,
         ):
             if self.engine_adapter.table_exists(table):
-                self.engine_adapter.ctas(
-                    f"{table}_backup", exp.select("*").from_(table), replace=True
-                )
+                with self.engine_adapter.transaction(TransactionType.DDL):
+                    backup_name = f"{table}_backup"
+                    self.engine_adapter.drop_table(backup_name)
+                    self.engine_adapter.ctas(
+                        backup_name, exp.select("*").from_(table), exists=False
+                    )
 
     def _migrate_rows(self) -> None:
         all_snapshots = self._get_snapshots(lock_for_update=True)