Lost grins from delayed wallet receive and finalize

[jasonxh]

Steps to reproduce:

1. grin wallet send -m file -d 1.grin 1
2. grin wallet tx -i <txid> shows all the involved inputs and change output.
3. Wait for a day. (Not sure of the exact time needed to repro, but at least a few hours).
4. grin wallet tx -i <txid> shows all the involved inputs, but the change output is no longer showing up.
5. grin wallet receive -i 1.grin, run either locally or from another wallet.
6. grin wallet finalize -i 1.grin.response. It shows the command is successful.
7. Wait sometime for the tx to be confirmed.
8. grin wallet tx -i <txid> still shows the tx as unconfirmed, but all inputs are now marked as spent, and the change output is still nowhere to be found. This results in lost change and a dangling tx.

I can then restore the entire wallet to recoup all the grins, but that results in loss of local tx data.

[yeastplume]

I'll see if there's anything removing the change output after a time period (there shouldn't be, sounds odd) but in the meantime grin wallet check_repair should restore missing outputs without any loss of tx data

[yeastplume]

Right, there's a dusty bit of code there that cleans unconfirmed outputs more than 500 blocks old.. obviously this needs to be rethought.