common: Moving .edeploy files in RELEASE directory

Priori this commit, we had the .edeploy files in the
/var/lib/deboostrap/install while the chroot was in
/var/lib/deboostrap/install/<RELEASE>

To make things a little bit more coherent, let's move the .edeploy file
inside the /var/lib/deboostrap/install/<RELEASE> directory too.