Preserver Symlinks in pyvenv.cfg paths

[rahuldevikar]

Use os.path.abspath() instead of os.path.realpath() when writing pyvenv.cfg
to match venv behavior. This preserves symlinks in paths, fixing issues with
Python installations accessed via symlinked directories (common in network-
mounted filesystems and scientific computing environments).

Fixes: #2770

Thanks for contributing, make sure you address all the checklists (for details on how see development documentation)

• ran the linter to address style issues (tox -e fix)
• wrote descriptive pull request text
• ensured there are test(s) validating the fix
• added news fragment in docs/changelog folder
• updated/extended the documentation