erp5.zeo: replace %(name)s with the export id in instanciation parameters for backup

This follows up commit 04ff4930eef733fc0305bb6a6b38f3ed9f204c60
s.r.apache-zope-backend: Add support for multiple listening IPs.

Minimal change, just made to listen identically on IPv4 and IPv6 addresses.
Settings are identical across all IPs.
erp5: Make backend apache also listen on IPv6.

Also, fix frontend request.
erp5: Drop frontend-related documentation.

Frontend support is desired, but current option set is too weak to cover
even simple cases.
erp5: Stop using slapos.cookbook:haproxy .

Fixes backend maxconn value: it's now equal to zope's number of threads.
Instead, generate configuration file from template and wrapper from
stand-alone recipe.
One local-only feature is lost: haproxy-ctl command is not present, but its
usage should be rare enough to not be a problem now. Socket is present
anyway, so any tool able to access a unix socket would do (ex: socat).
erp5: Publish deadlock debugger password as it may be generated.
erp5: Fix IPv6 apache configuration syntax.