Fix sequence state flags when interning.

The only change required to fix it was to add the "= true" which got
lost at some point in modifications. This change also removes the empty
packet with only the cleared flag (Perfetto may soon filter empty
packets) and removes the flags altogether for non interned cases.

Test: atest libnetworkstats_test
Change-Id: I6781349106a7c157ccace9d0cdff6d90190b69c5