delete --all doesn't work if you change profile

[medyagh]

if you change profile with minikube profile p1

it will not let you delete all
(you will have to be on default profile name)

medmac@~ $ minikube delete --all
💡  usage: minikube delete --all

medmac@~ $ minikube version
minikube version: v1.7.3
commit: 436667c819c324e35d7e839f8116b968a2d0a3ff
medmac@~ $ minikube delete --all
💡  usage: minikube delete --all
medmac@~ $ minikube profile list
|---------|-----------|---------|------------|------|---------|---------|
| Profile | VM Driver | Runtime |     IP     | Port | Version | Status  |
|---------|-----------|---------|------------|------|---------|---------|
| p1      | docker    | docker  | 172.17.0.3 | 8443 | v1.17.3 | Running |
| s1      | docker    | docker  | 172.17.0.2 | 8443 | v1.17.3 | Running |
|---------|-----------|---------|------------|------|---------|---------|

side effect of this code

	if deleteAll {
		if profileFlag != constants.DefaultMachineName {
			exit.UsageT("usage: minikube delete --all")
		}

this scenario doesn't happen that often thats why we didn't see this

[vikkyomkar]

/assign