samples: bluetooth: PAST: Disable for nrf52_bsim

The Zephyr controller does not support PAST, and there
is no other controller we can build upstream with these samples.

Disable these 2 samples for the nrf52_bsim until PAST
is supported by the controller.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>