clean up migration script for pool stat

Author: Cmdv

schema/migration-2-0045-20252107.sql schema/migration-2-0045-20250708.sqlschema/migration-2-0045-20252107.sql renamed to schema/migration-2-0045-20250708.sql

@@ -14,16 +14,8 @@ BEGIN
     );
 
     -- Then add constraint if it doesn't exist
-    DO $$
-    BEGIN
-      IF NOT EXISTS (
-        SELECT 1 FROM pg_constraint
-        WHERE conname = 'unique_pool_stat_epoch'
-      ) THEN
-        ALTER TABLE "pool_stat" ADD CONSTRAINT "unique_pool_stat_epoch"
+    ALTER TABLE "pool_stat" ADD CONSTRAINT IF NOT EXISTS "unique_pool_stat_epoch"
         UNIQUE ("pool_hash_id", "epoch_no");
-      END IF;
-    END $$;
 
     UPDATE schema_version SET stage_two = next_version ;
     RAISE NOTICE 'DB has been migrated to stage_two version %', next_version ;