In LND v0.15.1, batch_open_channel used p2tr by default
for change output. However, in a later version, a breaking
change has been fixed in FundPSBT to make the change type
configurable (default to p2wkh). As batch_open_channel
uses FundPsbt, we need to put back p2tr as default for
change output
This commit also removes the first connection attempt inside
`SetupStandbyNodes` as the nodes are always connected inside each
subtest. The error returned from connection is now logged for debugging.