Fix getActiveApexInfos for ApexManagerFlattenedApex

The for loop in existing code is redundant. It is supposed to filter out
some items when generating result.

Bug: 161150361
Test: m OVERRIDE_TARGET_FLATTEN_APEX=true
Test: atest ApexManagerTest
Change-Id: I0ff04b2b500f555ae6e34b9c87b7dc57e3bccaf3
1 file changed