Sweep up some dirt from fixing the payments #606

This card is rather funny and feel free to put in more than what is mentioned, if you have more ideas about doing some clean-up, removing any left-overs that refer to the old design.

a)
Remove the old table pending_payable from the schema of the database. It requires visiting the DbInitializer and also taking care of some tests aimed at this table.

Also write a database migration, but assuming that we complete the whole feature branch by parts and merge them at the end and so until then no merging in the master branch happens, you can reach for a little trick and optimize the code overhead by only extending the last written migration from the card number one. When the completed feature branch is presented to the testers finally, nobody will experience any issues with migrations from their old Node and because we should be doing only those partial review in the meantime, nobody could have during those times.

b)
Make sure the user interface is offered to the user with up-to-date information. That probably means we want to review the help messages in the clap_schema. Maybe it would be good to check even the document for the GUI team.

...edit...
c)
Integrate default values for the pending payable scan interval. They may be different by each chain.
This is the idea we had:
• Ethereum: 10 minutes
• Polygon: 3 minutes
• Base: 2 minutes