kiji-express: EXP-422. Disable parallel test execution until workaround for LocalJobRunner thread unsafety

issue: https://jira.kiji.org/browse/EXP-422
review: https://review.kiji.org/r/1722
commit: https://github.com/kijiproject/kiji-express/commit/ed5c7a26be093beecbcf3df1f0ff7425023fc0bb