Removes storage-driver directive from iso and docker runtime code

The code for the docker runtime (*Docker).setCGroup used to configure
the storage driver as well.. which could be seen as a wrong behaviour.

Also we're removing the storage-driver directive from the daemon.json
that are baked inside the iso..
However we want to see it.. it is not optimal to bake a config inside
the iso used by the vm driver; to build a new iso is painful

Author: x7upLime

deploy/iso/minikube-iso/arch/aarch64/package/docker-bin-aarch64/daemon.json

@@ -5,6 +5,5 @@
   "log-driver": "json-file",
   "log-opts": {
     "max-size": "100m"
-  },
-  "storage-driver": "overlay2"
+  }
 }

deploy/iso/minikube-iso/arch/x86_64/package/docker-bin/daemon.json

@@ -5,6 +5,5 @@
   "log-driver": "json-file",
   "log-opts": {
     "max-size": "100m"
-  },
-  "storage-driver": "overlay2"
+  }
 }

pkg/minikube/cruntime/docker.go

@@ -541,8 +541,7 @@ func (r *Docker) setCGroup(driver string) error {
 "log-driver": "json-file",
 "log-opts": {
 	"max-size": "100m"
-},
-"storage-driver": "overlay2"
+}
 }
 `, driver)
 	ma := assets.NewMemoryAsset([]byte(daemonConfig), "/etc/docker", "daemon.json", "0644")