Only wait for send status confirmation for unicasts

[puddly]

This allows for the downstream application to send two consecutive group commands without waiting for a send confirmation for the first.

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (e700caf) 99.75% compared to head (350936d) 99.75%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #537 +/- ## ======================================= Coverage 99.75% 99.75% ======================================= Files 57 57 Lines 4537 4539 +2 ======================================= + Hits 4526 4528 +2 Misses 11 11 ``` | [Impacted Files](https://codecov.io/gh/zigpy/bellows/pull/537?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zigpy) | Coverage Δ | | |---|---|---| | [bellows/zigbee/application.py](https://codecov.io/gh/zigpy/bellows/pull/537?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zigpy#diff-YmVsbG93cy96aWdiZWUvYXBwbGljYXRpb24ucHk=) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zigpy). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zigpy)

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[TheJulianJES]

Changes seem to work as expected btw

[pipiche38]

I don't know how it works with ezsp, but my experience on zigate is that by relying on this we were exhausting internal resources PDUs So it might be interesting to see the impact on large heavy network. And maybe having an easy way to disable this

[puddly]

On EmberZNet the only effect is that you run into NETWORK_BUSY more quickly, which is expected since more group commands can be sent at once (e.g. group light color commands usually send on() + move_to_color()).

[pipiche38]

And which layer handle the NETWORK_BUSY issue ? Is zigpy will do the retry or is that the above layer ?

[puddly]

Bellows tries three times if it's a transient error: https://github.com/zigpy/bellows/blob/e700caf2a50454d0060c3fcd5f67f4b49ebfce46/bellows/zigbee/application.py#L760-L786