Don't consider FOREGROUND exemption for visibility checks

To avoid conflicts with the ASM logic and in general because
BAL_ALLOW_FOREGROUND does not indicate that the app is actually visible,
consider this exemption only when non-visible exemptions are enabled.

Test: atest BackgroundActivityLaunchTests
Flag: EXEMPT bugfix
Bug: 352182359
Change-Id: Ia62686ca50bbfedc67c57c40ba94c299d66aedf4