tests: Bluetooth: ascs: Remove redunadant tests

This removes 2 tests related to ASCS handling ACL disconnection.
c3c83c70 modified the ACL disconection
behavior, so that ASE goes directly to idle state, not waiting in
releasing state for CIS disconnection. Thus the tests where state
machine waits for CIS disconnection can be removed now.

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>