Fix issue 4043: problems with ACI unit tests

1) Make AciTestCase base class of all ACI tests

2) Make AciTestCase clear test backend and default JE backend before and after each test

3) Make AciTestCase save a copy of the global ACIs before each test and restore the global ACIs after each test

4) Remove setup/teardown code from other ACI tests which is now performed by AciTestCase.

Tested on JDK5 and JDK6 for precommit and nightly targets.