[BEAM-10179] Clean-up URNJavaDoFn workaround in Go SDK. (apache#11899)

Now that the SDK has migrated to use the Dataflow runner v2, this is no longer required.

sdks/go/pkg/beam/core/runtime/exec/translate.go

@@ -337,7 +337,6 @@ func (b *builder) makeLink(from string, id linkID) (Node, error) {
  var u Node
  switch urn {
  case graphx.URNParDo,
- graphx.URNJavaDoFn,
  urnPerKeyCombinePre,
  urnPerKeyCombineMerge,
  urnPerKeyCombineExtract,

sdks/go/pkg/beam/core/runtime/graphx/translate.go

@@ -51,12 +51,7 @@ const (
  URNSessionsWindowFn = "beam:window_fn:session_windows:v1"
 
  // SDK constants
-
- // URNJavaDoFn is the legacy constant for marking a DoFn.
- // TODO: remove URNJavaDoFN when the Dataflow runner
- // uses the model pipeline and no longer falls back to Java.
- URNJavaDoFn = "beam:dofn:javasdk:0.1"
- URNDoFn = "beam:go:transform:dofn:v1"
+ URNDoFn = "beam:go:transform:dofn:v1"
 
  URNIterableSideInputKey = "beam:go:transform:iterablesideinputkey:v1"
  URNReshuffleInput = "beam:go:transform:reshuffleinput:v1"
@@ -239,7 +234,7 @@ func (m *marshaller) updateIfCombineComposite(s *ScopeTree, transform *pipepb.PT
  acID := m.coders.Add(edge.AccumCoder)
  payload := &pipepb.CombinePayload{
  CombineFn: &pipepb.FunctionSpec{
- Urn: URNJavaDoFn,
+ Urn: URNDoFn,
  Payload: []byte(mustEncodeMultiEdgeBase64(edge)),
  },
  AccumulatorCoderId: acID,
@@ -341,7 +336,7 @@ func (m *marshaller) addMultiEdge(edge NamedEdge) []string {
 
  payload := &pipepb.ParDoPayload{
  DoFn: &pipepb.FunctionSpec{
- Urn: URNJavaDoFn,
+ Urn: URNDoFn,
  Payload: []byte(mustEncodeMultiEdgeBase64(edge.Edge)),
  },
  SideInputs: si,
@@ -355,7 +350,7 @@ func (m *marshaller) addMultiEdge(edge NamedEdge) []string {
  case graph.Combine:
  payload := &pipepb.ParDoPayload{
  DoFn: &pipepb.FunctionSpec{
- Urn: URNJavaDoFn,
+ Urn: URNDoFn,
  Payload: []byte(mustEncodeMultiEdgeBase64(edge.Edge)),
  },
  }