Query "post" targets only when rebuild complete.

When we perform our initial query and then kick off an
async sorting task, we predictably see two list-ready
callbacks, both with doPostProcessing=true, first with
rebuildCompleted=false, then true. If we perform the
post-processing step both times, we'll double-log events,
double-query app prediction, etc. This is described in
more detail in b/209018315.

In this CL, we specifically ensure that the logging & APS
query only occur when the async rebuild is complete. This
is the minimal change to address the duplication while
restoring the general conditions of how this flow worked
prior to the introduction of the async step. In subsequent
CLs, there's room to optimize this flow or polish other
bugs that may have been introduced along with the async
step; for more discussion see the comments on this CL.

Note that we still have some disabled logging tests that
were supposed to assert the correct flow step-by-step,
but that regressed over time. Those tests will be
re-enabled in a subsequent CL, where we'll presumably need
to update the assertions to match the current flow.

Test: manual + `atest ChooserActivityTest`
Bug: 209018315
Change-Id: Ie1b786c46b4204ede26ab1face3f040dad77d26e