Drop a scale level from petascope when collection is not found

[Dimitar Misev]

If the rasdaman collection does not exist, the scale level cannot be removed from petascope:

  INFO [2019-09-17 16:33:39] RasUtil@123: Executing rasql query: DELETE FROM Global_Sentinel2_L1C_TCI_4 WHERE oid(Global_Sentinel2_L1C_TCI_4)=3037185
rasj[0] RasNetImplementation.getResponse: query failed, errNo=355, lineNo=1, colNo=13, token=Global_Sentinel2_L1C_TCI_4
 ERROR [2019-09-17 16:33:40] ExceptionUtil@56: Caught an exception 
petascope.rasdaman.exceptions.RasdamanCollectionDoesNotExistException: Error: collection name does not exist in rasql query: DELETE FROM Global_Sentinel2_L1C_TCI_4 WHERE oid(Global_Sentinel2_L1C_TCI_4)=3037185
        at petascope.util.ras.RasUtil.executeRasqlQuery(RasUtil.java:176)
        at petascope.util.ras.RasUtil.executeRasqlQuery(RasUtil.java:108)
        at petascope.util.ras.RasUtil.deleteFromRasdaman(RasUtil.java:233)
        at petascope.service.PyramidService.deleteScaleLevel(PyramidService.java:381)
        at petascope.wcst.handlers.DeleteScaleLevelHandler.handle(DeleteScaleLevelHandler.java:79)
        at petascope.controller.handler.service.KVPWCSTServiceHandler.handleDeleteScaleLevel(KVPWCSTServiceHandler.java:194)
        at petascope.controller.handler.service.KVPWCSTServiceHandler.handle(KVPWCSTServiceHandler.java:128)
        at petascope.controller.PetascopeController.requestDispatcher(PetascopeController.java:199)
        at petascope.controller.PetascopeController.handleGet(PetascopeController.java:124)
...