Move system server pullers off background thread

The background thread is prone to severe delays in processing time near
boot, which causes pull timeouts and event queue overflow in statsd. The
vast majority of pullers use the DIRECT_EXECUTOR to execute pulls in the
incoming binder thread, so move these pulled atoms to do the same thing.
More context is in the bug and linked docs.

Bug: 298133385
Test: verified via boot traces that the pull durations are shorter and
that the pulls no longer happen in the background thread

Change-Id: I67a3d583cc13d9547dfe7108897e95f4a5238d26