Simplify the "fixHideOverlay" flagging

- Completely separated the code

- Fixed a bug where calling for the same window with surfaceShown=false
  twice would cause it to be double-counted.

- Factored out an "effective" for readability

Test: atest 'WindowManagerServiceTests'
Fix: 402186473
Flag: com.android.window.flags.fix_hide_overlay_api
Change-Id: I14af1e8207e0aaacd63d7d160f2775310e8b922b