Drop the `kwargs` forwarding from buildroot.run() to subprocess.run().
We do not use it other than for `stdin=subprocess.DEVNULL`. Set that
option directly instead.
Doing the kwargs forwarding mixes the argument namespaces and is very
hard to read. It is not clear from the call-site which argument goes to
buildroot.run() and which to subprocess.run().
Lastly, it requires us to manually fetch `check` just to make pylint
happy. Lets just drop this dance and make the API explicit.
d4f40362ec