Advertise with a shorter hostname by default (can be disabled via a
chicken bit), instead of "Android_[32 characters]" as the hostname.
This should allow decreasing the size of APF programs necessary for
advertising offload, and make the advertiser compatible with Matter
use-cases. Some Matter implementations (notably CHIP) interpreted
the example in "4.3.1.1. Host Name Construction" of the spec as
if only 16 character hostnames needed to be supported, despite not
following the rule to construct the hostname based on link-layer
addresses.
The hostname changed once in T when migrating from mdnsresponder to the
current advertiser implementation, so changing the format again is
unlikely to create problems, especially since this keeps the "Android_"
prefix.
Bug: 341141476
Test: atest
Change-Id: Ic8311f41a1a943ec8230203fcd74eda7a26a691c
5e99d1fea1