Sync novolume image

Summary:
Offer OS upgrade to applications dependent images.

Ref T1679.

Image entry point

The runsvdir-init script, used for images based on Debian Jessie, controls
how this image run runit.

On Jessie, it saved environment, then call a script added by the Debian package
maintainer, runsvdir-start. That start script cleared environment and then
launch runit with /etc/service as services directory.

On Buster and Bullseye, runsvdir-start isn't available anymore. The first idea
was to ask images to directly call runit themselves. Yet, to ease maintenance,
it's clearly more efficient to have an unique entry point and be able to tweak
how we run the services. As such, we still provide runsvdir-init.

Test Plan: Rebuild PHP applications images

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1679

Differential Revision: https://devcentral.nasqueron.org/D2523