tests: explicitly disable bzlmod for pip_parse_vendored example

[rickeylev]

Bazel at head enables bzlmod by default, but the pip_parse_vendored example doesn't work
under bzlmod.

To fix, explicitly disable bzlmod because vendoring requirements.bzl files isn't necessary
under bzlmod. This is because the pip bzlmod extension handles creating repos directly
from the locked requirements file (which is the output of the pip dependency resolution
process).

While we're here, also enable incompatible_generate_aliases = True, in preparation for
that being switched.