When MdnsMultinetworkSocketClient stops using a socket (when
isSocketActive starts returning false), the packet handler should be
removed from that socket. The code only removed it from the
mSocketPacketHandlers map without clearing it from the socket.
This caused packets to be handled potentially many times, affecting
performance.
Bug: 406623719
Bug: 408324621
Test: atest
Flag: EXEMPT bugfix
Change-Id: I3d1117a4b847f3b95a01fc8a5997a53655ef608a