Raise on exception no longer raises for prefect signals

[cicdw]

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• adds new tests (if appropriate)
• updates CHANGELOG.md (if appropriate)
• updates docstrings for any new functions or function arguments, including docs/outline.toml for API reference docs (if appropriate)

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What does this PR change?

The raise_on_exception no longer re-raises Prefect Signals during execution.

Why is this PR important?

This PR helps target the re-raises to "unexpected" errors, for a better debugging experience when using things like switch control flow tasks.