Settings performance testing

1. Add storage page as test target.
2. Set screen timeout to 2 hours to avoid screen timeout during testing.
3. Force close settings before launching each page.
4. Reset screen timeout after testing.
5. Increase test times from 10 to 100.

Test: atest SettingsPerfTests:LaunchSettingsTest
Change-Id: I52c4f15e47a2a83219212de1262a13b3b196c21c