Allow the simulator to pass the End_Run aux message to clients

[yhwen]

Fixes # .

Description

Allow the ServerRunner to pass END_RUN aux messages to the clients when running the simulator. Still keeps the behavior to avoid un-necessary error messages if client run finishes earlier when sending the messages.

Types of changes

• [x] Non-breaking change (fix or new feature that would not break existing functionality).
• [ ] Breaking change (fix or new feature that would cause existing functionality to change).
• [ ] New tests added to cover the changes.
• [ ] Quick tests passed locally by running ./runtest.sh.
• [ ] In-line docstrings updated.
• [ ] Documentation updated.