Concurrent parallel invocations can lose worker-options files

Crash

On Ubuntu 24.04 with Python 3.12 and Mypy 2.3.1, four concurrent Mypy invocations using --num-workers=4 intermittently failed to start their build workers. Several workers reported:

FileNotFoundError: [Errno 2] No such file or directory: '.mypy_cache/.worker_options.<id>.data'
Failed to establish connection with worker: No status file found

Full GitHub Actions log: https://github.com/adamtheturtle/literalizer/actions/runs/34489393511/job/102911865600

The four commands shared the working directory and default .mypy_cache, but each checked a different temporary Python file. The failure is intermittent; an unchanged rerun passed. Serializing the invocations and using one Mypy worker avoids it.

This resembles #21393, but that report is specifically a macOS test failure; this occurrence was on Linux with concurrent consumer invocations.