Remove 10 blocks confirmation rule for UTXO

Previously bifrost BTC chain client implement a rule that asgard is not going to spend UTXO that has less than 10 confirmations in case there is re-org happening on BTC chain, however with the confirmation counting logic implemented in bifrost as well , all the BTC amount that is available to asgard should be safe to spend.

As such, bifrost BTC chain client should be able to ditch the 10 confirmation RULE