build: delete umd.js from the final package (#3431)
build: delete umd.js from the final package (#3431)

This file is not necessary and breaks closure compiler.
ReactiveX/RxJS,benlesh/RxJS,benlesh/RxJS,Brocco/RxJS,Brocco/RxJS,trxcllnt/RxJS,jayphelps/rxjs,martinsik/rxjs,martinsik/rxjs,ReactiveX/rxjs,kwonoj/RxJS,ReactiveX/RxJS,martinsik/rxjs,ReactiveX/rxjs,Brocco/RxJS,jayphelps/rxjs,jayphelps/rxjs,trxcllnt/RxJS,ReactiveX/rxjs,benlesh/RxJS,ReactiveX/rxjs,ReactiveX/RxJS,martinsik/rxjs,jayphelps/rxjs,ReactiveX/RxJS,trxcllnt/RxJS,kwonoj/RxJS,benlesh/RxJS,kwonoj/RxJS,kwonoj/RxJS,Brocco/RxJS,trxcllnt/RxJS,jayphelps/rxjs