The python policy plugin argument parsing was very brittle and would
fail when passed extra flags such as `--tracing <file>` or
`--logtostderr`. We now properly parse these standard plugin falgs (see
plugin#buildPluginArguments). Note that the flags are currently not
being used by the policy plugins.
Nodejs does not suffer from the same issue because we are already using
`minimist` to parse the arguments.
Fixes https://github.com/pulumi/pulumi/issues/11092