Notify telemetry only every second about the tx pool status (#6605)

Before this was done for every imported transaction. When a lot of
transactions got imported, the import notification channel was filled.
The underlying problem was that the `status` call is read locking the
`validated_pool` which will be write locked by the internal submitting
logic. Thus, the submitting and status reading was interferring which
each other.

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Co-authored-by: GitHub Action <action@github.com>