This update permanently removes a previously resurrected VoIP component related to OnSIP. A recent update accidentally reintroduced this feature, and this commit ensures it's no longer present in the system. This simplifies the codebase and avoids potential confusion.

While `voip_onsip` should have been removed altogether in 19.1, a commit adding new icons accidentally resurrected it.

This commit removes it for good.

Forward-Port-Of: odoo/enterprise#116773