[29.x] depends: remove xinerama extension from libxcb #33238

1. 
   fanquake commented at 11:47 am on August 22, 2025: member

   Backports #33217 to the 29.x branch. Same rationale as #33217. xinerama was obseleted well before it’s removal in Qt6.
2. depends: remove xinerama extension from libxcb

   This is listed on https://doc.qt.io/qt-5.15/linux-requirements.html as
   "recommended", however doesn't seem to be needed, and the fact that it's
   no-longer installed by default on modern linux distros, is
   annoying/confusing for users. See:
   
   https://github.com/bitcoin/bitcoin/issues/30061
   https://bitcoin.stackexchange.com/questions/122646/libxcb-xinerama0-library-required-by-bitcoin-qt
   https://github.com/bitcoin/bitcoin/pull/33197
   https://github.com/bitcoin/bitcoin/issues/32097
   
   Github-Pull: #33217
   Rebased-From: 3d9314f3838c3b369bb79a64479f110c35b78644

   d9532415da
3. guix: remove libxcb-xinerama.so.0 from allowed libs

   Github-Pull: #33217
   Rebased-From: decc3671c88bb3acdf137c6bc46892f99319104e

   1e8637c064
4. doc: update release notes for 29.x 6b8a782bbd
5. fanquake requested review from hebasto on Aug 22, 2025
6. DrahtBot added the label Backport on Aug 22, 2025
7. 
   DrahtBot commented at 11:47 am on August 22, 2025: contributor

   The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

   Code Coverage & Benchmarks

   For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/33238.

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8. 
   fanquake commented at 12:41 pm on August 22, 2025: member

   Guess we can’t backport this unless we also backport the removal in Qt. Will take a look.
9. DrahtBot added the label CI failed on Aug 22, 2025

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fanquake DrahtBot

Review Requested
hebasto

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Backport CI failed