bsc: Fix regression in TC_assignment_emerg_setup_deny_bts

A recent commit introduced a regression which made
TC_assignment_emerg_setup_deny_bts fail.

The problematic commit (see hash below) set "pars.ra :=
f_rnd_ra_emerg()" in the helper function, which made the BSC early
reject the CHAN RQD with ImmAssRej in the case the BTS policy forbids
emergency calls.
In that scenario, rejection can be done early because there's no need to
wait to find out which MSC it is aimed at.
This scenario, however, is already being validated by test TC_chan_rqd_emerg_deny.

The scenario TC_assignment_emerg_setup_deny_bts was testing is actually
one where CHAN RQD doesn't contain reason="emergency call", which means
BTS doesn't early reject it, but only knows about it being an emergency
call when a CC Emergency Setup is sent to it, time at which it releases
the call.

Hence, this commit sets back pars.ra = f_rnd_ra_emerg() only on the ..._deny_msc
testcase, since it's the only test really needing it.

Fixes: 14076d3b721030c5f0610403cbc7e75a6eed5351
Related: OS#5849
Change-Id: I8d342e5938f6293ae45ee399796417651768af5d
1 file changed