bluetooth: controller: update unittests for LLCP to use proper ZTEST API

Update unittests for the following areas/controll procedures
- API
- collision handling
- invalid PDUs
- unsupported procedures
- buffer allocation
- TX queue
- Data Length Update
- PHY update
- Encryption
- Ping
- Version
- Channel map update
- Min. used channels
- Connection update
- SCA
- Terminate connection
- CTE request
- CIS create
- CIS terminate

Also moved the internal API tests from the ull_llcp* files
to the proper unittest C-file

Unused files  are removed

Signed-off-by: Andries Kruithof <andries.kruithof@nordicsemi.no>