Short-circuit PIC permission checks for system_server

While the PIC-based permission checks are relatively cheap when there's
a hit, they are unnecessary for checks against system_server. Hoist the
system_server permission bypass out of the cache, avoiding locks or
small temporary objects in the cache query for such cases.

Bug: 414189094
Bug: 416218069
Test: presubmit
Flag: EXEMPT trivial performance fix
Change-Id: I06f2ffb2a0cb552e9f5541432465c527d77d8b24