tests: bluetooth: bsim: Pretend that the controller supports CIS

The test relies on enabling connection iso features in the host. As the
controller does not yet support them, this configuration does not really
make sense. But because the test is not using this functionality, we
work around it by pretending the controller supports it.

Signed-off-by: Rubin Gerritsen <rubin.gerritsen@nordicsemi.no>