WifiPermissionsUtil: Use new lightweight API for targetSdkVersion fetch

New API added in S (b/164459559) which provides a more optimized API for
targetSdkVersion fetch. Switch the wifi stack to use that.

Bug: 164459559
Test: atest com.android.server.wifi
Change-Id: Iaced3dbc0288ebe2af8417f89329eab3130ba23f
2 files changed
tree: 34b7d74ac9511a8da9b972a65bfd88c0d5261d05
  1. apex/
  2. service/
  3. metrics_pdd_hook.py
  4. PREUPLOAD.cfg