systemd/systemd: move udevadm into udev subpkg

Fixes a conflict between systemd and systemd-udev where apk thinks they both provide cmd:udevadm:

ERROR: unable to select packages:
  systemd-256.11-r2:
    conflicts: systemd-udevd-256.11-r2[cmd:udevadm=256.11-r2]
  systemd-udevd-256.11-r2:
    conflicts: systemd-256.11-r2[cmd:udevadm=256.11-r2]

[ci:ignore-count]
[ci:skip-build] already built in CI

Part-of: !6334

extra-repos/systemd/systemd/APKBUILD

@@ -6,7 +6,7 @@ pkgname=systemd
 # currently tracking git MR
 pkgver=256.11
 _pkgver="musl-v${pkgver//_/-}-split-usr"
-pkgrel=2
+pkgrel=3
 pkgdesc="System and service manager"
 url="https://github.com/systemd/systemd"
 arch="all !ppc64le !s390x" # blocked by pmboostrap not supporting
@@ -259,6 +259,7 @@ udevd() {
 	provider_priority=100
 
 	amove etc/udev
+	amove usr/bin/udevadm
 	amove usr/lib/libudev*
 	amove usr/lib/systemd/system/initrd-udevadm-cleanup-db.service
 	amove usr/lib/systemd/system/sockets.target.wants/systemd-udev*