tests: BT: migrate connectionless tx to ztest register

Migrating the test suites to the register functionality allows the
main.c source to focus on the state of the system instead of "which"
test to run. In this example, test_main() now calls:
* ut_bt_setup() and updates the state
* common_create_adv_set(), updates the state, and notifies the
  registered tests that the state has been updated which would trigger
  a run.
* common_delete_adv_set(), updates the state, and again notifies
  the registered tests that the state has been updated.

Signed-off-by: Yuval Peress <peress@chromium.org>