DO NOT MERGE: Revert: use legacy way to get tcp packet count

In Q, legacy way to get tcp packet count is not planned to be
supported. Users who use this unsupported API e.g., data stall
detection are also planned to be removed.

Thus, this change reverts a5c3fb10 which is the short term
solution in P.

Bug: 110443385
Test: atest FrameworksNetTests
Change-Id: Ia09f908edbf194b9aa873a3bdd5aee7b6fcb16bc