fix(net): do not resolve IPs when netloc contains a port

[Ndukiye]

Proposed Commit Message

fix(util): include port-stripped hostname in IP fast-path check

The existing IP fast-path optimization only checked parsed_url.netloc,
which includes port information. This meant IP URLs with ports (e.g.
http://169.254.169.254:80) did not benefit from the optimization and
still triggered DNS resolution.

This improves the existing logic by using parsed_url.hostname, which
correctly excludes port information while preserving IP detection.

Fixes #6557

Additional Context

Test Steps

Tested with:
tox -e py3

Merge type

• Squash merge using "Proposed Commit Message"
• Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[holmanb]

Thanks for the proposal.

[holmanb]

One nit, otherwise this looks good to me.

[holmanb]

Thanks, @Ndukiye!