Fix the BFSL calling app SDK level check

- Use the actual calling UID, not mRecentCallingUid
- Special case calling UID 1000

Bug: 324101525
Test: atest ActivityManagerFgsBgStartTest
Test: atest "CtsAppFgsStartTestCases:android.app.cts.fgsstarttest.ActivityManagerNewFgsLogicTest#testForCurrent"
should pass, with http://ag/26150406, on an eng build.

Change-Id: I9200fa318f73b9e7455a9b27b42d7fb9338c1e71