Fix for #2293 - vrouter UVE's generated by collector not deleted after hostname change

When a generator node is deleted, only the UVEs originated by the generator are removed. The UVE originated by the Collector (ModuleServerState) with the <host-name>:<module-name> of the generator as the key is not removed and hence it shows up in the generator list (/uves/generators). Fixed an issue with the extraction of table name in delrequest.lua, because of which the keys are not removed from the table.