Clean up remote_bootstrap_service-test
Clean up remote_bootstrap_service-test

* The FlagSaver is no longer needed because it is now part of KuduTest
* Replace CHECKs with ASSERTs

Change-Id: I05e20f87e055aaa51d4990812ee865f1790747cd
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/4292
Tested-by: jenkins
Reviewed-by: Todd Lipcon <2c763d726a8c2f6afda9be7e0e56a2caa6bb5e6b@cloudera.com>

InspurUSA/kudu,cloudera/kudu,cloudera/kudu,InspurUSA/kudu,cloudera/kudu,andrwng/kudu,andrwng/kudu,cloudera/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,EvilMcJerkface/kudu,helifu/kudu,EvilMcJerkface/kudu,cloudera/kudu,andrwng/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,andrwng/kudu,helifu/kudu,andrwng/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,cloudera/kudu,helifu/kudu,EvilMcJerkface/kudu,EvilMcJerkface/kudu,andrwng/kudu,InspurUSA/kudu,InspurUSA/kudu,EvilMcJerkface/kudu,InspurUSA/kudu,andrwng/kudu,andrwng/kudu