ttcn3-asterisk: pjsip.conf: Use reliable provisional responses if peer supports it
The default 100rel=yes won't use reliable provisional responses unless the peer "requires" it, while we should instead be using them if the peer "supports" it.
ttcn3-asterisk: Set mp_ims_imei matching pjsip.conf
Since recently, the testsuite validates the IMEI received at IMS Core over REGISTER Contact header matches the one configured at Asterisk config file. Hence, add the same value to Asterisk_Tests.cfg so it can match the value.
