Fix install-go cache key #3026

Job	Run time
build / Build	7m 52s
build-windows / Build	7m 4s
Integration Tests (localstorage)	4m 18s
Integration Tests (kubeflags)	8m 50s
Integration Tests (etcdrestore)	3m 59s
Integration Tests (startup)	12m 17s
Integration Tests (etcdsnapshot)	9m 41s
Integration Tests (custometcdargs)	3m 11s
Integration Tests (longhorn)	6m 4s
Integration Tests (certrotation)	3m 59s
Integration Tests (flannelnone)	4m 2s
Integration Tests (cacertrotation)	5m 8s
Integration Tests (secretsencryption)	5m 5s
Integration Tests (windows)	1m 43s
	1h 23m 13s

Provide feedback