[CI] Fix CI script test subprocess environment

[tlopex]

This fixes CI script tests that accidentally run helper scripts with the wrong Python interpreter.

Some tests call run_script(..., env={...}) to pass test-specific environment variables. subprocess.run treats env as a full environment replacement, so the subprocess lost the current PATH. Since these scripts use a shebang like:

#!/usr/bin/env python3

they could fall back to the system Python instead of the active test Python.

In the wheel test environment this caused the CI helper scripts to run under Python 3.8, even though TVM requires Python >=3.10. Importing ci/scripts/jenkins/git_utils.py then failed on PEP 604 annotations such as:

Any | None
tuple[str, str] | None

with:

TypeError: unsupported operand type(s) for |: '_SpecialForm' and 'NoneType'

This patch updates tests/python/ci/test_utils.py::run_script to merge test-provided environment variables into os.environ instead of replacing the entire environment. This preserves the active Python/PATH while still allowing each test to override or add variables.

[gemini-code-assist]

Warning

You have reached your daily quota limit. Please wait up to 24 hours and I will start processing your requests again!