make chunkifying work for application tests.

This makes -parallelizeSuites work for application tests, too.  It used
to only work for logic tests, presumably becasue the code needed to call
otest-query-* was easiest to do inside of the `*AppTestRunner` classes
where `environmentOverrides` already existed (maybe @yiding can confirm).

Tested by running `-parallelizeSuites 2` and observing that application
test suites were run in groups of 2.