8339591: Mark jdk/jshell/ExceptionMessageTest.java intermittent

Reviewed-by: lucy

Author: MBaesken

test/langtools/jdk/jshell/ExceptionMessageTest.java

@@ -26,6 +26,7 @@
  * @bug 8185108
  * @summary Test exception().getMessage() in events returned by eval()
  * @run testng ExceptionMessageTest
+ * @key intermittent
  */
 
 import java.util.HashMap;