ReqMgr databases consistency checks and cleanup

ReqMgr prod databases (CouchDB CMS web couchdb/reqmgr_workload_cache and
Oracle)

There were 498 requests in the CouchDB which were not present in Oracle.
Probably failed during injection and since ReqMgr injection is not implemented
as an atomic operation a request was put in CouchDB but not in Oracle.
Checked with Edgar, requests in question were not tracked in GlobalMonitor and
were all agreed to be deleted from CouchDB. Also, since some CouchDB document
fields are not properly filled (#4380) by ReqMgr (e.g. RequestStatus), it's
not possible to tell more about those requests just by ReqMgr itself.

Total 498 requests deleted from CouchDB.

This patch is part of #4388