HAWQ-1122. Convert elog::ERROR to elog::WARNING in translator and throw exception to stop execution
HAWQ-1122. Convert elog::ERROR to elog::WARNING in translator and throw exception to stop execution

This is cherry-picked from greenplum-db/gpdb@386861225f3a027f45de8f21d73f2d2ec40129ec

stanlyxiang/incubator-hawq,jianlirong/incubator-hawq,huor/incubator-hawq,wengyanqing/incubator-hawq,stanlyxiang/incubator-hawq,wengyanqing/incubator-hawq,jianlirong/incubator-hawq,wengyanqing/incubator-hawq,wengyanqing/incubator-hawq,jianlirong/incubator-hawq,outofmem0ry/incubator-hawq,jianlirong/incubator-hawq,jianlirong/incubator-hawq,stanlyxiang/incubator-hawq,lavjain/incubator-hawq,lavjain/incubator-hawq,outofmem0ry/incubator-hawq,jianlirong/incubator-hawq,stanlyxiang/incubator-hawq,huor/incubator-hawq,lavjain/incubator-hawq,lavjain/incubator-hawq,jianlirong/incubator-hawq,huor/incubator-hawq,huor/incubator-hawq,lavjain/incubator-hawq,outofmem0ry/incubator-hawq,stanlyxiang/incubator-hawq,outofmem0ry/incubator-hawq,wengyanqing/incubator-hawq,wengyanqing/incubator-hawq,outofmem0ry/incubator-hawq,lavjain/incubator-hawq,outofmem0ry/incubator-hawq,lavjain/incubator-hawq,huor/incubator-hawq,lavjain/incubator-hawq,outofmem0ry/incubator-hawq,huor/incubator-hawq,stanlyxiang/incubator-hawq,outofmem0ry/incubator-hawq,jianlirong/incubator-hawq,huor/incubator-hawq,wengyanqing/incubator-hawq,stanlyxiang/incubator-hawq,wengyanqing/incubator-hawq