Revert fix and instead update test expectation

internal/plans/planfile/tfplan.go

@@ -1403,7 +1403,7 @@ func actionInvocationToTfPlan(action *plans.ActionInvocationInstanceSrc) (*planp
 
 	ret := &planproto.ActionInvocationInstance{
 		Addr:     action.Addr.String(),
-		Provider: action.ProviderAddr.Provider.String(),
+		Provider: action.ProviderAddr.String(),
 	}
 
 	switch at := action.ActionTrigger.(type) {

internal/stacks/stackplan/planned_change_test.go

@@ -992,7 +992,7 @@ func TestPlannedChangeAsProto(t *testing.T) {
 						ProviderConfigAddr:    "example.com/webhooks/http",
 						Invocation: &planproto.ActionInvocationInstance{
 							Addr:     "action.webhook.notify",
-							Provider: "example.com/webhooks/http",
+							Provider: `provider["example.com/webhooks/http"]`,
 							ActionTrigger: &planproto.ActionInvocationInstance_LifecycleActionTrigger{
 								LifecycleActionTrigger: &planproto.LifecycleActionTrigger{
 									TriggeringResourceAddr:  "example_resource.main",