Do not register into round if too many utxos are banned

[hynek-jina]

If a user has banned more than 40% of total non-private utxos or sum of banned utxos amounts is greater than 40% then they should not register to the next round for a certain period of time (1 hour).

It could work as a prevention of unknown bugs like #8307

[matejkriz]

fixed by #8484 ?

[bosomt]

AFAIK there is no way to test it on our side right ?

[matejkriz]

You can test it, at least on testnet where it's more OK to ruin the round to have banned UTXO, but I believe it's ok to test it during normal coinjoin testing...