Allow discard in 4.1 writer_yielding_db_unavailable_error_on_rollback

Author: injectives

tests/stub/routing/scripts/v4x1_no_routing/writer_yielding_db_unavailable_error_on_rollback.script

@@ -8,9 +8,14 @@ C: BEGIN {"db": "adb"}
 S: SUCCESS {}
 C: RUN "RETURN 1 as n" {} {}
 S: SUCCESS {"fields": ["n"]}
-C: PULL {"n": 1000}
-S: RECORD [1]
-   SUCCESS {"type": "r"}
+{{
+    C: PULL {"n": 1000}
+    S: RECORD [1]
+       SUCCESS {"type": "r"}
+----
+    C: DISCARD {"n": -1}
+    S: SUCCESS {}
+}}
 C: ROLLBACK
 S: FAILURE {"code": "Neo.TransientError.General.DatabaseUnavailable", "message": "Unable to rollback"}
 +: RESET