Fix lndhub balances with on-chain topups

Removes the bitcoind RPC config entirely, so lndhub only uses LND's
transaction monitoring. The bitcoind integration is broken as is.

site-cookbooks/kosmos-bitcoin/templates/lndhub.config.js.erb

@@ -4,9 +4,6 @@ let config = {
   rateLimit: 200,
   forwardReserveFee: 0.01, // default 0.01
   intraHubFee: 0.003, // default 0.003
-  bitcoind: {
-    rpc: 'http://<%= @bitcoin_rpc_user %>:<%= @bitcoin_rpc_pass %>@<%= @bitcoin_rpc_host %>/wallet/wallet.dat',
-  },
   redis: {
     port: 6379,
     host: '127.0.0.1',