fix: Retain execution data between partial executions (new flow)

Summary

The run data has been behaving weird with the new execution flow since the last update:

Before:

https://github.com/user-attachments/assets/4a4c2eab-0646-4694-a597-76ce12d75484

But even before that it hasn't been working the way you'd expect, e.g. nodes after the destination node that had run data would keep their run data until the execution finished which means they would stay green until the end of the execution and only then turn gray.

All of this is related to moving the run data management for partial executions to the backend without accounting for a way to keep the FE state in sync with it.

This PR does 2 things to fix this:

fix a bug where the FE would prune the run data even if the new partial execution flow is enabled
send the run data with the executionStarted started event and update the FE with it

After:

https://github.com/user-attachments/assets/d6b7b759-3a4f-4112-9835-6712cf6d812d

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/PAY-2255/the-fe-looses-all-run-data-between-runs-if-the-new-partial-execution

Review / Merge checklist

[x] PR title and summary are descriptive. (conventions)
[x] ~Docs updated or follow-up ticket created.~
[x] Tests included.
[ ] PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

Attention: Patch coverage is `85.71429%` with `2 lines` in your changes missing coverage. Please review.	Files with missing lines	Patch %	Lines
...ckages/cli/src/workflow-execute-additional-data.ts	50.00%	1 Missing :warning:
packages/core/src/WorkflowExecute.ts	0.00%	1 Missing :warning:

n8n-io / n8n