Replace flags with check for debug build

These flags were never intended to be ramped to 100%, so changing from flag to Build.IS_DEBUGGABLE to keep informing developers without annoying end users.

Test: atest CtsWindowManagerBackgroundActivityTestCases
Bug: 433530796
Bug: 433529760
Flag: EXEMPT flag removal bal_show_toasts_blocked.bal_show_toasts_blocked bal_show_toasts_blocked.bal_additional_logging
Change-Id: Ic954f6525fd4a43353a18af7aa379e14ae0a115f