Fix EZP-23159: clear project container cache pre composer install/update

Problem: when updating eZ Publish through composer, any service change can potentially break the process with fatal errors/exceptions.

The usual fix is then to `rm -rf ezpublish/cache/*`

However, it should NOT be necessary to fully clear all the caches, as it is an issue specific to the project configuration container.
This introduces a new script to remove such files, as well as composer.json pre-install / pre-update cmds.