Fix missing advertising set callbacks

I didn't realize that OnAdvertisingSetEnable is also called when you
*disable* the advertiser.

Unit tests also didn't catch it because nothing tested what happens when
you enable, then disable.

Test: unit
Bug: 263435509
Change-Id: I56f3149e622515e314292044352600a12d2dd568
(cherry picked from commit 212357f2)
Merged-In: I56f3149e622515e314292044352600a12d2dd568