Reroute nodes display "frontend_only" label instead of user-set title

### Description

Reroute nodes (e.g. Reroute from rgthree) no longer display their user-set title. Instead, they show a `frontend_only` label, making it impossible to identify what the reroute is connected to.

### Steps to Reproduce
1. Add a Reroute (rgthree) node to the workflow
2. Set a descriptive title on the reroute node
3. Observe that the title is replaced with a "frontend_only" label

### Expected Behavior
Reroute nodes should display their user-set title so users can identify their purpose.

### Actual Behavior
Only a `frontend_only` label is shown, removing all user context.

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*Split from #9979*

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-9997-Reroute-nodes-display-frontend_only-label-instead-of-user-set-title-3256d73d365081f2b54eecc4ab1d55a6) by [Unito](https://www.unito.io)