Fix work service and ImportDB Job

Fix work service and ImportDB Job

1. Increased DefaultVisibilityTimePeriod to 30 min from 5 min. Without this, concurrent runs of ImportDB job happens. In other words, concurrent imports, renames and cleanup
2. Also, tweaked ImportDB job a bit so that, in the unlikely event that rename DB fails, it is detected and tried again after 5 min by using Suspend and Resume. And, only allow rename after an import is known to have completed successfully