…ic#53859)

* Remove punctuation from translation

We already had a colon on both uses of this key, resulting in '::' on
the page.

* Ignore 409 errors from our signal creation

In my experience these are always due to a rule being run multiple times
on the same document, generating a duplicate signal with a (correctly)
duplicate id. Only if we encounter non-409 errors do we log a message to
the user.

* Hide 409 errors during signal creation

These are expected and potentially confusing to the user. Instead, we
only show unexpected errors.

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>