workflows: use btcd for macOS

To increase the speed from 40m per run to roughly 20m per run.

.github/workflows/main.yml

@@ -407,14 +407,8 @@ jobs:
           go-version: '${{ env.GO_VERSION }}'
           key-prefix: integration-test
 
-      - name: install bitcoind
-        run: |
-          wget https://bitcoincore.org/bin/bitcoin-core-${BITCOIN_VERSION}.0/bitcoin-${BITCOIN_VERSION}.0-arm64-apple-darwin.tar.gz
-          tar zxvf bitcoin-${BITCOIN_VERSION}.0-arm64-apple-darwin.tar.gz
-          mv bitcoin-${BITCOIN_VERSION}.0 /tmp/bitcoin
-
       - name: run itest
-        run: PATH=$PATH:/tmp/bitcoin/bin make itest-parallel tranches=${{ env.TRANCHES }} backend=bitcoind shuffleseed=${{ github.run_id }}
+        run: make itest-parallel tranches=${{ env.TRANCHES }} shuffleseed=${{ github.run_id }}
 
       - name: Zip log files on failure
         if: ${{ failure() }}