Remove thread delegation when checking grants.

This code was leftover from previous attempts at avoiding deadlock,
and itself was causing deadlocks with the latest strategy.

Reproduced deadlock in linked bugs, and confirmed that this CL fixes
the underlying deadlock.

Bug: 115619667, 157863128
Test: atest CtsAppSecurityHostTestCases:android.appsecurity.cts.AppSecurityTests#testPermissionDiffCert
Change-Id: I9a8e5828090adebae1bfc306219c4b42d0c97432