Stop MdnsServiceTypeClient send on socket destroy

MdnsServiceTypeClient should stop sending when it is removed due to its
socket being destroyed.

On null networks (downstream interfaces) that may have multiple sockets,
this should only happen once the last socket used by the (null) network
has been destroyed.

Bug: 278635632
Test: atest
Change-Id: Ie1808840bd68678f2af7b71bdd8f3be377c14424
7 files changed