Update the Exception message to diagnose the port unavailability issue

### 📝 Description of the feature

While executing workbench script in customer environment, it failed to launch workbench due to port unavailability.

The Exception message is not clear to diagnose the port unavailability issue, so request you to modify the Exception message accordingly.

### 💡 Steps for implementing the feature

_No response_

### 🔗 Useful links and references

_No response_

The issue does not name a file, test, or entry point. Locate the workbench launch path and the exception raised when its port is unavailable, then clarify the diagnostic message and verify the resulting error behavior with the relevant existing tests.

Written by the indexing model from the issue text.