build, qt: bump Qt5 version to 5.15.5

Summary:
This is a minor Qt bump to drop a few patches. It also has some style changes.

core#24668

Qt 5.15.3 release is a patch release made on the top of Qt 5.15.2. As a patch
release, Qt 5.15.3 does not add any new functionality but provides bug fixes
and other improvements.

https://code.qt.io/cgit/qt/qtreleasenotes.git/about/qt/5.15.3/release-note.md

• dropped patches:
  • patches/qt/fix_bigsur_style.patch
• adjusted patches:
  • patches/qt/fix_limits_header.patch

Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

build, qt: drop fix_no_printer.patch

The removed patch is not required since switching Qt version from
5.12.11 to 5.15.2.

build, qt: use one patch per line in depends/packages/qt.mk

core#25719

build: Bump Qt to 5.15.5 in depends

qt: use patch over sed for guix CROSS_LIBRARY_PATH change

This is a backport of core#24668 and core#25719

Depends on D13918

Test Plan: gitian builds, guix build

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13926