Remove deprecated code for LTS 2019

We want to remove the deprecated code for Nuxeo Platform 10.10.

All code present in Nuxeo Platform deprecated since 5.9.x - 6.0 should be removed.

Deprecated extension points could also be removed if and only if contributing to this extension point logged a warning message at startup.
These two calls should be present:

DeprecationLogger.log(message, "9.1");
Framework.getRuntime().getMessageHandler().addWarning(message);