Docker-in-docker: Updates docker-init with "pkill"

[samruddhikhandale]

Fixes : devcontainers/images#729

When the universal image is built with latest docker-in-docker Feature, it fails to start docker daemon as containerd does not start (Reported in #671 (comment)) .The image is trying to retry the docker daemon startup, but as containerd (or/and dockerd) is not in a good state before, it fails to restart causing docker ps to fail.

find /run /var/run -iname 'docker*.pid' -delete || :
find /run /var/run -iname 'container*.pid' -delete || :

We do have these commands ^ but it simply removes the PID files, does not stop/clean the dockerd and containerd daemons

🧪 Tested these PR changes with universal:dev@sha256:b7a147f15c61f02b8220d1719431f205f65e48267ffed93e0b9c642c14cf956a image, docker ps is successful.

[joshspicer]

looks very reasonable to me 👍