Draft: Singlenode short-chain setup for transaction testing

[alexeykoren]

Here is a non-final PR just to illustrate where the changes were made to enable Zcash_Tx_Tool

[oxarbitrage]

Thanks! This is related to https://github.com/ZcashFoundation/zebra/issues/8280

[arya2]

This was redundant now that all of the hard-coded changes can be set as part of Zebra's configuration.