sdist: remove .egg-info and setup.cfg from sdist

[kevinjqliu]

Rationale for this change

Follow up to #2601
clean up .egg-info/ and setup.cfg from sdist

Are these changes tested?

Yes

Check the new sdist

rm -rf dist build pyiceberg.egg-info
uv build --sdist
tar -tzf dist/pyiceberg-*.tar.gz | grep -E "(build/|setup.cfg|\.egg-info)"

Diffed too

diff -qr ./dist/pyiceberg-0.10.0 ~/Downloads/nightly/sdist/ | sort

differ
    Files ./dist/pyiceberg-0.10.0/Makefile and /Users/kevinliu/Downloads/nightly/sdist/Makefile differ
    Files ./dist/pyiceberg-0.10.0/PKG-INFO and /Users/kevinliu/Downloads/nightly/sdist/PKG-INFO differ
    Files ./dist/pyiceberg-0.10.0/dev/.rat-excludes and /Users/kevinliu/Downloads/nightly/sdist/dev/.rat-excludes differ
    Files ./dist/pyiceberg-0.10.0/pyproject.toml and /Users/kevinliu/Downloads/nightly/sdist/pyproject.toml differ
new
    Only in ./dist/pyiceberg-0.10.0/tests: .DS_Store
    Only in ./dist/pyiceberg-0.10.0: MANIFEST.in
    Only in ./dist/pyiceberg-0.10.0: setup.py
removed
    Only in /Users/kevinliu/Downloads/nightly/sdist: build-module.py
    Only in /Users/kevinliu/Downloads/nightly/sdist: poetry.lock

In sdist, ran RAT check and tests

make check-license
make test-coverage

Are there any user-facing changes?

No

[kevinjqliu]

cc @geruh