MCP service creator - Tool return type placeholder is `undefined`

### Description

<img width="1162" height="494" alt="Image" src="https://github.com/user-attachments/assets/4f49eb59-aad9-4b10-9047-1a14b74b4e02" />

### Steps to Reproduce

Create an MCP service and add a new tool.

### Version

https://github.com/wso2/product-integrator/issues

### Environment Details (with versions)

_No response_