Re-spawning osmo-bts is no longer necessary. For quite some time now, it has been able to attempt OML link re-establishment in a loop instead of exit()ing.
Additionally, using respawn.sh makes crashes harder to detect. Whether we should restart the IUT process and continue executing the remaining test cases after a crash is debatable. However, none of the other testsuites (except ttcn3-pcu-test, which actually requires restarting osmo-pcu after each TC) use respawn.sh for that purpose.
