Disable broken grilo plugins

Description:

The following three grilo plugins are broken, cause Totem and other clients to crash, and were already removed in upstream:

• appletrailers
• euronews
• raitv

Upstream is sadly not much active anymore and there is no plan to release a new grilo-plugins version in the near future.

The broken plugins are already disabled downstream in multiple distributions including Debian (Ubuntu) and Fedora.

Please, consider disabling them in the Arch package as well.

Thanks!

Additional info:

https://salsa.debian.org/berto/grilo-plugins/-/commit/5963980e59aa92f82b29a1928379d25fc25e48e7

https://src.fedoraproject.org/rpms/grilo-plugins/c/c5265fa5763eb1cb3ab1abf5e0c2672ab6f7a401

Steps to reproduce:

1. Open Totem.
2. Switch to the "Channels" tab.
3. Try using any of the pre-installed plugins.