Enable REMOVE_SPENT_UTXOS by default in the env variables

[Kartiiyer12]

As for day to day exchange opertaions, we do not need historical spent utxo data. So we are enabling REMOVE_SPENT_UTXOS and setting REMOVE_SPENT_UTXOS_LAST_BLOCKS_GRACE_COUNT to have unspent utxos for 30 days by default.

[matiwinnetou]

+1

[matiwinnetou]

@tienna can you try to take care of it for 1.3.1, new pull request to a develop branch after we merge today 1.3.0 and release it?

[linconvidal]

Default: 30 days