Fix panic when no services in namespace with --all specified

[spowelljr]

Fixes: #19933

Before:

$ minikube service --all -n some-namespace-that-doesnt-exists
panic: runtime error: index out of range [0] with length 0

goroutine 1 [running]:
k8s.io/minikube/cmd/minikube/cmd.init.func35(0x10818caa0?, {0x14000984930, 0x0, 0x3?})
	/Users/powellsteven/repo/minikube/cmd/minikube/cmd/service.go:117 +0x1208
github.com/spf13/cobra.(*Command).execute(0x10818caa0, {0x14000984840, 0x3, 0x3})
	/Users/powellsteven/go/pkg/mod/github.com/spf13/[email protected]/command.go:989 +0x81c
github.com/spf13/cobra.(*Command).ExecuteC(0x10818c4e0)
	/Users/powellsteven/go/pkg/mod/github.com/spf13/[email protected]/command.go:1117 +0x344
github.com/spf13/cobra.(*Command).Execute(...)
	/Users/powellsteven/go/pkg/mod/github.com/spf13/[email protected]/command.go:1041
k8s.io/minikube/cmd/minikube/cmd.Execute()
	/Users/powellsteven/repo/minikube/cmd/minikube/cmd/root.go:174 +0x550
main.main()
	/Users/powellsteven/repo/minikube/cmd/minikube/main.go:95 +0x250

After:

$ minikube service --all -n some-namespace-that-doesnt-exists

❌  Exiting due to SVC_NOT_FOUND: No services were found in the 'some-namespace-that-doesnt-exists' namespace.
You may select another namespace by using 'minikube service --all -n <namespace>'

[k8s-ci-robot]

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This pull-request has been approved by: medyagh, spowelljr

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