Increase timeout for libjdwp tests

Since libjdwp has more threads running concurrently then the old
internal jdwp implementation does it can sometimes take slightly
longer to finish certain test tasks (most notably shutdown). This was
causing the tests to timeout occasionally on the chrome-buildbots.

Bug: 68839405
Test: ./art/tools/run-libjdwp-tests.sh --mode=host
Change-Id: I8d443662c40de27d490248e8df5d77b43f78267c