Codegen cannot handle negative steps in maps

[Spielopoly]

Description
I think there are actually two separate bugs here, but they are related.

1. Codegen produces wrong code for negative steps in maps with sequential schedule.
2. Codegen produces wrong code for symbolic steps, which are negative at runtime with default schedule.

To Reproduce
reproduce.py

Expected behavior
All testcases above should pass

Desktop (please complete the following information):

• OS: Ubuntu 24.04.3 LTS