unify and bump _WIN32_WINNT definition to Windows 8.1 #27235

Job	Run time
config	7s
fuzz smoke test	1m 3s
win+VS build	0s
win build	5m 6s
static-analysis	5m 38s
win+Meson build	3m 56s
sparse	3m 35s
osx-clang (macos-14)	16m 1s
osx-gcc (macos-14)	20m 23s
osx-reftable (macos-14)	19m 27s
osx-meson (macos-14)	20m 58s
documentation	7m 21s
rust-analysis	1m 45s
almalinux-8 (almalinux:8)	10m 40s
linux-leaks (ubuntu:rolling)	28m 15s
linux-reftable (ubuntu:rolling)	13m 14s
linux-meson (ubuntu:rolling)	13m 29s
debian-11 (debian:11)	9m 58s
linux-reftable-leaks (ubuntu:rolling)	28m 21s
fedora-breaking-changes-meson (fedora:latest)	9m 30s
linux-sha256 (ubuntu:rolling)	12m 39s
linux-musl-meson (alpine:latest)	7m 54s
linux32 (i386/ubuntu:focal)	8m 38s
linux-breaking-changes (ubuntu:rolling)	12m 21s
linux-TEST-vars (ubuntu:20.04)	12m 44s
linux-asan-ubsan (ubuntu:rolling)	34m 16s
win+VS test	0s
win+Meson test (0)	9m 58s
win+Meson test (1)	10m 54s
win+Meson test (4)	7m 18s
win+Meson test (2)	9m 42s
win+Meson test (3)	6m 37s
win+Meson test (9)	8m 2s
win+Meson test (8)	8m 32s
win+Meson test (5)	9m 39s
win+Meson test (7)	7m 28s
win+Meson test (6)	12m 55s
win test (7)	5m 27s
win test (9)	10m 15s
win test (1)	7m 55s
win test (2)	6m 41s
win test (6)	5m 32s
win test (0)	6m 6s
win test (3)	8m 37s
win test (5)	9m 15s
win test (8)	8m 43s
win test (4)	8m 34s
	7h 55m 29s

Provide feedback