JDK 9 RFR of JDK-8023897: Replace/update/rename executeAndCatch in various tests to assertThrows

[Amy Lu]

Please review this test-only change.

Some java/util tests use a function executeAndCatch which essentially 
asserts that an exception is thrown, while some other tests use 
assertThrows for doing the same work. For both cases, with jtreg 
upgraded to testng 6.9.5 (CODETOOLS-7901639), test can then leverage 
TestNG Assert.assertThrows

Please review the patch to update executeAndCatch and assertThrows to 
Assert.assertThrows for java/util testng tests.

bug: https://bugs.openjdk.java.net/browse/JDK-8023897
webrev: http://cr.openjdk.java.net/~amlu/8023897/webrev.00/

Thanks,
Amy