Fix race condition when cancelling/speeding up onchain transactions

[ramirotw]

Description
Follow up of #1797 (comment)

Possible fix:

I think the solution is to keep track of all of the hashes until one of them is mined to avoid the race condition.

Currently there's a chance that when submitting either a cancel or speed up transactions the original transaction that is being replaced gets mined before the replacement tx. This causes the app to display that tx as Pending since the old transaction reference got removed.