Run CTS GeneratedTests across all three compute modes: SYNC, ASYNC, BURST.

Before this change, we only run with the default (SYNC) compute mode.

It may be useful to run other (non-GeneratedTests) tests across all
three compute modes; but this requires individually modifying all such
tests.

Bug: 128618282

Test: NeuralNetworksTest_static (and confirm by inspecting logcat that
      one GeneratedTest is running as expected -- not affected by CTS changes)
Test: CtsNNAPITestCases (and confirm by inspecting logcat that one
      GeneratedTest is running as expected -- across all three compute modes)

Change-Id: Ie4b4d90329ae9e1b61a863d82d69c05645a46b8f