fix(test-runner): handle Windows path lists safely

[tianma-if]

Fixes #57149.

Summary

• split runner path lists without treating Windows drive-letter colons as separators
• keep CI-generated colon-joined relative file lists working when Windows uses ; as os.pathsep
• replace unencodable progress glyphs on legacy Windows pipes so done callbacks do not emit UnicodeEncodeError tracebacks

Tests

• .venv/bin/python -m pytest tests/test_run_tests_parallel.py -q -k "path_list or progress_print or bare_value"
• .venv/bin/python -m pytest tests/test_run_tests_parallel.py -q
• .venv/bin/python -m ruff check scripts/run_tests_parallel.py tests/test_run_tests_parallel.py
• scripts/run_tests.sh tests/test_run_tests_parallel.py -q

[alt-glitch]

This was generated by AI during triage.

Duplicate of #57152 — both fix #57149 in scripts/run_tests_parallel.py with the same two changes (Windows drive-letter-safe path-list split + UTF-8/errors='replace' progress output). Same code-site and mechanism, different helper names. #57152 is the earliest open.

[tianma-if]

Closing as duplicate of #57152 per triage; the earlier PR covers the same Windows path-list/test-runner fix. Thanks.