fix(ui): remove labels from dynamically added ports (#4140)

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### What changes were proposed in this PR?
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This PR removes the automatic labeling of dynamically added input and
output ports. Previously, when users added new ports to operators, the
ports were automatically labeled with their port IDs which caused
inconsistencies (e.g., "input-1", "input-2", "output-1", "output-2").

**Changes:**
- Modified the `addPort` method in `WorkflowActionService` to set the
`displayName` to an empty string instead of using the `portID`
- This change affects all dynamically added ports (both input and
output)

**Before:**
<img width="441" height="198" alt="Screenshot 2025-12-29 at 4 07 24 PM"
src="https://github.com/user-attachments/assets/ced2f0a9-bdcf-4eff-9865-becf63e4466f"
/>

**After:**
<img width="270" height="181" alt="Screenshot 2025-12-29 at 4 07 31 PM"
src="https://github.com/user-attachments/assets/f98a27de-31a4-45f2-a75e-5b61fd658468"
/>

### Any related issues, documentation, discussions?
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This PR resolves #3894.

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Tested manually.

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No.

Author: seongjinyoon

frontend/src/app/workspace/service/workflow-graph/model/workflow-action.service.ts

@@ -249,7 +249,7 @@ export class WorkflowActionService {
 
     const port: PortDescription = {
       portID,
-      displayName: portID,
+      displayName: "",
       allowMultiInputs,
       isDynamicPort: true,
       dependencies: [],