testing/babeld: use supervise-daemon

If babeld crashes, it often leaves its pidfile behind, preventing it
from starting up again without manual intervention.

Using supervise-daemon to supervise babeld, and disabling the use of a
pidfile with babeld's -I '' command-line option resolves this issue.
7 jobs for !9274 with babeld-1.9.2-r1 in 20 seconds
detached
Status Job ID Name Coverage
  Lint
failed #144513
docker-alpine x86_64 allowed to fail
lint

00:00:10

 
  Build
failed #144518
docker-alpine ci-build aarch64
build-aarch64

00:00:07

failed #144519
docker-alpine ci-build armv7
build-armv7

00:00:07

failed #144517
docker-alpine ci-build ppc64le
build-ppc64le

00:00:10

failed #144516
docker-alpine ci-build s390x
build-s390x

00:00:05

failed #144515
docker-alpine ci-build x86
build-x86

00:00:06

failed #144514
docker-alpine ci-build x86_64
build-x86_64

00:00:07

 
Name Stage Failure
failed
build-x86_64 Build
No job log
failed
build-s390x Build
No job log
failed
build-x86 Build
No job log
failed
build-aarch64 Build
No job log
failed
build-armv7 Build
No job log
failed
build-ppc64le Build
No job log
failed
lint Lint
No job log