Revert "AMBARI-3474. Add empty string as a valid config value (ncole)"

This reverts commit 883d33eb9b0f911b0b24d48acdb675dea55da8df.
Revert Jobs-related changes from "AMBARI-2702. UI cleanup after merge branch-1.4.0 into trunk. (Andrii Tkach via srimanth)" (yusaku)
Revert Jobs-related changes from "AMBARI-2677. Merge from branch-1.4.0 (ncole)" (yusaku)
AMBARI-3496. NameNode Enable HA and Rollback Wizard text changes. (yusaku)