Salt api honors --log-file correctly

[dwoz]

Make sure we verify the proper path when the --log-file cli options is
passed via the commandline.

What issues does this PR fix or reference?

Fixes: #59880

[waynew]

suggestion (non-blocking): Could add a contextmanager for this:

from contextlib import contextmanager

@contextmanager
def mktemp():
    fname = tempfile.mktemp()
    try:
        yield fname
    finally:
        try:
            os.remove(fname)
        except OSError:
            pass

Then it's just

with mktemp() as pidfile, mktemp() as logfile, patch.object(...):

and the rest of this boilerplate disappears.