JShell tests: clean-up tests before integration.

Before integration Kulla to JDK9 all excluded tests for JShell should be cleaned up:
1. Now if a test is excluded, it has "@Test(enabled = false)" annotation, so jtreg does not indicate nothing. Instead of using the annotation, "@ignore" jtreg tag should be used. In this case, we won't miss that a test will never be run.
2. Each of the excluded tests should have an open bug in JBS. The bug id should be written in "@ignore" tag.