add TCP data stall metrics

Current metrics contains only DNS signal. Given TCP info is
also considered to detection data stall, the related TCP
information should be included into metrics.

Bug: 150182763
Test: atest NetworkStackTests NetworkStackNextTests
Test: Test with ./out/host/linux-x86/bin/statsd_testdrive 121
      to ensure log properly
Change-Id: I5e306299f3cf4f49c46f161cd0aa4cb40d1ab76e