Use MdnsUtils helper methods to construct query packets

This no-op change uses MdnsUtils#createRawDnsPacket to construct
query packets instead of MdnsPacketWriter. This refactoring sets
the stage for future support of constructing multiple query
packets.

Bug: 312657709
Test: atest FrameworksNetTests NsdManagerTest
Change-Id: I404ec52e97635eed9d965d7c7ceaf6e726386d64
3 files changed