Turn screen off when doing pno stress test

This CL has below changes:
- Turn screen off to trigger pno scans correctly
- Simplify the code flow about pno stress test and wifi selector test

Bug: 120760521
Test: Local
Change-Id: Ice32f2545b2326177e9e19d51c4734152ae860f1
(cherry picked from commit 54912698163f87d24464f1b75c3e5547a08e7cdb)
1 file changed
tree: 6296b13dda6093af0a9a24c54892c0b18a1762ca
  1. acts/
  2. tools/
  3. wts-acts/
  4. Android.mk
  5. PREUPLOAD.cfg