fix(pip): do not use experimental_index_url for publish_deps (#3311)

Currently, experimental_index_url will trigger network access (by the
bzlmod extension
logic) as it figures out the wheels. This is problematic because this
network
access always occurs, even if a user isn't using the publish tool.
Additionally,
failed network accesses can get Bazel into stuck state requiring `bazel
shutdown`
to fix it.

To fix, don't  use experimental_index_url for the publish tool deps.

Once bazelbuild/bazel#24777 is merged, we can roll it back,
but then we may need to check-in the `MODULE.bazel.lock` file into git.

This should be no-op for most users because the publisher is usually run
from with `host == exec`, but there is a small chance that people will
hit #2241.

Work towards #2937