[Designer] Remove the hard coded child workflow dynamic apis and use backend apis.

### Severity

P2 - High (Major functionality broken)

### Describe the Bug with repro steps

This bug is to track the WI where we need to remove the hard coded client fetch calls for invoke workflow dynamic calls and directly use the service api. This would reduce the latency of the call and help user load the workflow faster.

### What type of Logic App Is this happening in?

Standard (Portal)

### Are you experiencing a regression?

_No response_

### Which operating system are you using?

Windows

### Did you refer to the TSG before filing this issue? https://aka.ms/lauxtsg

Yes

### Workflow JSON

```json

```

### Screenshots or Videos

_No response_

### Environment

-

### Additional context

_No response_