[2.5] --- Fix custom pythonpath missing

[yhwen]

Fixes # .

Description

Fixed the custom pythonpath missing issue for the simulator client run execution. Set up the custom PYTHONPATH before SImulatorRunner should be carried over to the client run execution.

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.

[chesterxgchen]

@yhwen please make the same PR for 2.6

[YuanTingHsieh]

/build

[yhwen]

/build