textproc/py-pylibxml2: rm patch that scans garbage

Remove a local patch that scans stack garbage for a pattern and then uses
the pointer after the array has been filled with actual data. This can
cause random segfaults.

The patch is under textproc/libxml2, but the patched file is only used by
textproc/py-pylibxml2.

The UTF-8 issue this was intended to fix was fixed upstream in a more
comprehensive way in 2.11.0 with this commit:
https://gitlab.gnome.org/GNOME/libxml2/-/commit/76c6da420923f2721a2e16adfcef8707a2454a1b

PR: 286439 279034
Approved by: desktop (makc)
Tested by: vvd
MFH: 2025Q2

(cherry picked from commit d5b2d60fc76964a3e5b8f50d2992bd751f688f04)