btstack only supports central-initiated, so this allows us to have a test
that works on both (ble_mtu.py), and then another one for just the NimBLE
supported behavior (ble_mtu_peripheral.py).
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Use the same `wait_for_event` in all tests that doesn't hold a reference to
the event data tuple and handles repeat events.
Also fix a few misc reliability issues around timeouts and sequencing.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
