Update record receipt time on records updated

The receipt time in the MdnsResponse need to be updated every time new
packet is received. And then the record refreshing logic could calculate
remaining TTL correctly.

Bug: 285260665
Test: atest CtsNetTest FrameworksNetTests
Change-Id: Ib7a290ea0ea8e552c71c657696397e8114fcee52
6 files changed