I've been debugging a Shelly [bluetooth
proxy](https://www.home-assistant.io/integrations/shelly/#bluetooth-support)
feature, which didn't like b-parasite's advertising. It swallowed it before proxying it to HA.
I compared to both ATC and the legacy b-parasite advertising
(pre-nrf-connect) and found it to be related to the
non-connectable/non-scannable settings. Until this PR, we were
mistankenly settings the advertising to scannable, although with no
scannable data. The Zephyr code that sets this parameter based on the
scannable data is [here](c0fcd35531/subsys/bluetooth/host/adv.c (L860)).
My bet is that some scanners like ESPHome are okay with this, but Shelly
is not. Either way, I believe this PR makes the advertisements more
compliant.
We were previously relying on the default values (100ms, 150ms). This
PR makes it easier to test and configure parameters for different
tradeoffs between range / power consumption (#98).
