stack/erp5: completely remove cloudooo

I would like to apply it around the wednesday 27th of September, please be prepared to upgrade your sites !

This MR provides two commits :

• Remove Cloudooo from stack/erp5 ;
• Add parameter to configure Cloudooo URL.

By default, ERP5 will be configured (at instanciation) to use the public cloudooo cluster on https://cloudooo.erp5.net/ (defined on Default System Preference).

But you can choose which URL to use. Here is an example of instanciation parameter : {"cloudooo-url":"https://example.com/"}

caution /!\ as concequences Cloudooo will become orphean if you upgrade your site from a slapos computer or from a webrunner :

• from a slapos computer, the Cloudooo instance won't be requested anymore by the root instance. So here would be the suggested steps to upgrade :
  • run slapos node software to build the new software ;
  • configure Cloudooo URL on your site to point to an external Cloudooo ;
  • stop Cloudooo service ;
  • request Cloudooo stop (or destroy) ;
  • once software built, run slapos node instance.
• from webrunner, the differences is that it's not possible to destroy (or stop?) the Cloudooo instance. Here are the suggested steps to upgrade :
  • configure Cloudooo URL on your site to point to an external Cloudooo ;
  • stop Cloudooo service ;
  • then hack to make slapos proxy to think Cloudooo does not exist anymore (stopped or destroyed) ;
  • click Play.