gatewaysv2: gatewaysdeposit, potential dos vector via combining gateway utxos

[Alrighttt]

It is possible for a user to combine a large amount of the token utxos from gateways token address. I have demonstrated this on CCV2 chain here, 905ea21091c2ddd76147551bbcfed0d0a4685672ed92dee88f511c8052a2ca5f.

I believe this could be a potential dos attack vector. I am looking at the validation code, and I see no method for "un-combining" these, so it could result in the entire chain/gateway relying on a singular utxo at all times.