fix(news): use :gh: instead of :issue: and remove duplicate blurb

Address review feedback from StanFromIreland:
- Changed :issue:`145492` to :gh:`145492` (correct syntax for GitHub issues)
- Removed duplicate NEWS blurb added by blurb_it

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: mvanhorn

Misc/NEWS.d/next/Library/2026-03-09-00-00-00.gh-issue-145492.457Afc.rst

@@ -1,3 +1,3 @@
 Fix infinite recursion in :class:`collections.defaultdict` ``__repr__``
 when a ``defaultdict`` contains itself. Based on analysis by KowalskiThomas
-in :issue:`145492`.
+in :gh:`145492`.