[BUG] sync_node_executions fails for workflows with FailureNodes

[machichima]

Tracking issue

Part of https://github.com/flyteorg/flyte/issues/6490

Why are the changes needed?

Getting error ValueError: Missing node from mapping: fn0 when using remote.wait on an execution that has FailureNode specified and the execution fails

What changes were proposed in this pull request?

Adding failure node to node_mapping

How was this patch tested?

Setup process

Screenshots

Check all the applicable boxes

• [ ] I updated the documentation accordingly.
• [x] All new and existing tests passed.
• [x] All commits are signed-off.

Related PRs

Docs link

Summary by Bito

This pull request fixes a bug in workflow handling by improving the node mapping logic to include failure nodes during execution. It also introduces new tests to validate this functionality, enhancing robustness in failure scenarios.