adpf: Add a target duration scale factor for hboost junk frame detection

Add the scale factor so that it avoid adding the barely missed frames
into the junk frames statistics.

Bug: 204204746
Test: atest libperfmgr_test; atest libadpf_test;
      adb shell dumpsys android.hardware.power.IPower/default;
      check adpf sessions' traces.
Change-Id: I959a2ff83d7984e7a34d6abea74661eb8bb3fa6f