[RFC][IMP] modules, models: remove inherits
When removing a module, all its models (and their fields) are also removed. However inherits of such models had to be cleaned up manually.
This is inspired by https://github.com/odoo/upgrade/pull/7280
upgradeci retry with always only account
In principle this should be the default behaviour. However that would break backwards compatibility with code that used to deal with the inherits after the removal of the module/model. The flags preserving worse-legacy-behavior are not ideal then, but probably necessary without a versioning system. Takes?
In order to catch all potential issues: upgradeci retry with all modules in all versions
(that will take a while...)
