RFR (xs) 8172678: JShell Tests: Disable CompletionSuggestionTest.testBrokenClassFile2()

[Robert Field]

Please review...

Bug:

      JShell Tests: Disable CompletionSuggestionTest.testBrokenClassFile2()
     https://bugs.openjdk.java.net/browse/JDK-8172678

Related issues:

     jdk/jshell/CompletionSuggestionTest.java failed with AssertionError
     https://bugs.openjdk.java.net/browse/JDK-8171829

     JShell: addToClasspath fails intermittently
     https://bugs.openjdk.java.net/browse/JDK-8172676

Webrev:

     http://cr.openjdk.java.net/~rfield/8172678v0.webrev/

-Robert