main/busybox-initscripts: use supervisor-daemon for udhcpd

Without this change udhcpd fails to start as it is compiled without the
pidfile option (#11841). While certainly possible to enable the pidfile
option, I believe that we should work towards replacing pidfiles and
instead rely on supervisor-daemon. Many aports (unbound, wpa_supplicant,
…) already use supervisor-daemon.. I would suggest that we also start
using it for busybox initscripts. This is just a start, the other
scripts can be converted later on.

Fixes #11841
7 jobs for !11446 with udhcpd-supervisor-daemon in 1 minute and 36 seconds
latest detached
Status Job ID Name Coverage
  Lint
failed #186587
docker-alpine x86_64 allowed to fail
lint

00:00:21

 
  Build
passed #186592
docker-alpine ci-build aarch64
build-aarch64

00:00:26

passed #186593
docker-alpine ci-build armv7
build-armv7

00:00:34

passed #186591
docker-alpine ci-build ppc64le
build-ppc64le

00:00:46

passed #186590
docker-alpine ci-build s390x
build-s390x

00:00:20

passed #186589
docker-alpine ci-build x86
build-x86

00:00:22

passed #186588
docker-alpine ci-build x86_64
build-x86_64

00:00:26

 
Name Stage Failure
failed
lint Lint
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