provisioner/salt-masterless: fix crash processing connection config

The code here was previously assuming that d.State() was equivalent to
the schema.ProvRawStateKey due to them both being of type InstanceState,
but that is in fact not true since a state object contains some transient
information that is _not_ part of the persisted state, including the
connection information we need here.

Calling ResourceData.State() constructs a _new_ state based on its stored
values, so the constructed object is lacking this transient information.
We need to use the specific state object provided by the caller in order
to get access to the transient connection configuration.

Unfortunately there is no automated test coverage for this because we have
no good story for testing provisioners that use "communicator". While such
tests could potentially be written, we'd like to get this in somewhat
quickly to unblock a release, rather than delaying to design and implement
some sort of mocking system for this.

builtin/provisioners/salt-masterless/resource_provisioner.go

@@ -116,6 +116,7 @@ func applyFn(ctx context.Context) error {
 
 	o := ctx.Value(schema.ProvOutputKey).(terraform.UIOutput)
 	d := ctx.Value(schema.ProvConfigDataKey).(*schema.ResourceData)
+	connState := ctx.Value(schema.ProvRawStateKey).(*terraform.InstanceState)
 
 	p, err := decodeConfig(d)
 	if err != nil {
@@ -123,7 +124,7 @@ func applyFn(ctx context.Context) error {
 	}
 
 	// Get a new communicator
-	comm, err := communicator.New(d.State())
+	comm, err := communicator.New(connState)
 	if err != nil {
 		return err
 	}