fix(actions v2): send event_payload on event executions again (#10651)

# Which Problems Are Solved

It was noticed that on actions v2 when subscribing to events, the
webhook would always receive an empty `event_payload`:
```
{
    "aggregateID": "336494809936035843",
    "aggregateType": "user",
    "resourceOwner": "336392597046099971",
    "instanceID": "336392597046034435",
    "version": "v2",
    "sequence": 1,
    "event_type": "user.human.added",
    "created_at": "2025-09-05T08:55:36.156333Z",
    "userID": "336392597046755331",
    "event_payload":
    {}
}
```

The problem was due to using `json.Marshal` on the `Event` interface,
where the underlying `BaseEvent` prevents the data to be marshalled:

https://github.com/zitadel/zitadel/blob/131f70db3423b80da1b038a822da59c908e4ffa6/internal/eventstore/event_base.go#L38

# How the Problems Are Solved

The `Event`s `Unmarshal` function is used with a `json.RawMessage`.

# Additional Changes

none

# Additional Context

- closes https://github.com/zitadel/zitadel/issues/10650
- requires backport to v4.x

internal/eventstore/v3/push_test.go

@@ -262,8 +262,8 @@ func Test_mapCommands(t *testing.T) {
 
 func TestEventstore_queueExecutions(t *testing.T) {
 	events := []eventstore.Event{
-		mockEventType(mockAggregate("TEST"), 1, nil, "ex.foo.bar"),
-		mockEventType(mockAggregate("TEST"), 2, nil, "ex.bar.foo"),
+		mockEventType(mockAggregate("TEST"), 1, []byte(`{"test":"test"}`), "ex.foo.bar"),
+		mockEventType(mockAggregate("TEST"), 2, []byte("{}"), "ex.bar.foo"),
 		mockEventType(mockAggregate("TEST"), 3, nil, "ex.removed"),
 	}
 	type args struct {

internal/repository/execution/queue.go

@@ -27,10 +27,13 @@ func NewRequest(e eventstore.Event, targets []target.Target) (*Request, error) {
 	if err != nil {
 		return nil, err
 	}
-	eventData, err := json.Marshal(e)
+	// The underlying BaseEvent omits the data when using json.Marshal so we have to unmarshal it manually.
+	var eventData json.RawMessage
+	err = e.Unmarshal(&eventData)
 	if err != nil {
 		return nil, err
 	}
+
 	return &Request{
 		Aggregate:   e.Aggregate(),
 		Sequence:    e.Sequence(),