When env is passed to subprocess.run() we should pass all existing
environment variables. This fixes crash on Windows:

Fatal Python error: failed to get random numbers to initialize Python

Fatal Python error: _Py_HashRandomization_Init: failed to get random
numbers to initialize Python
Python runtime state: preinitialized

The usage of the --password flag when invoking the mysql CLI has the
potential of exposing the password in plain text if the command happens
to crash due to the inclusion of args provided to
subprocess.run(check=True) in the string representation of the
subprocess.CalledProcessError exception raised on non-zero return code.

Since this has the potential of leaking the password to logging
facilities configured to capture crashes (e.g. sys.excepthook, Sentry)
it's safer to rely on the MYSQL_PWD environment variable instead even
if its usage is discouraged due to potential leak through the ps
command on old flavors of Unix.

Thanks Charlie Denton for reporting the issue to the security team.

Refs #24999.

Co-Authored-By: Mariusz Felisiak <felisiak.mariusz@gmail.com>

subprocess.run()'s args parameter accepts path-like objects on Windows
since Python 3.8.