Remove the deleted stats from map

The xt_qtaguid module removes per uid stats when an app get uninstalled.
So eBPF map should not store the uninstalled stats either. This change
help fix the unknown iface problem as well.

Bug: 77987430
Test: android.app.usage.cts.NetworkUsageStatsTest
Change-Id: Ieb08833ecc35f76d27769042f197d889470faf7f