CI: don't download bitcoind for FreeBSD build.

It didn't work, and it was downloading the Linux binary anyway!

```
  2025-04-11 02:37:12 (1.61 MB/s) - ‘bitcoin-27.1-x86_64-linux-gnu.tar.gz’ saved [48920073/48920073]

  tar: Error opening archive: Failed to open 'bitcoin-27.1-x86_64-linux-gnu.tar.bz2'
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

.github/workflows/bsd.yml

@@ -45,11 +45,6 @@ jobs:
             python3.10 -m pip install --upgrade pip
             curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain nightly-2024-11-28
 
-            cd /tmp/ || exit 1
-            wget https://bitcoincore.org/bin/bitcoin-core-${{ matrix.bitcoind-version }}/bitcoin-${{ matrix.bitcoind-version }}-x86_64-linux-gnu.tar.gz
-            tar -xf bitcoin-${{ matrix.bitcoind-version }}-x86_64-linux-gnu.tar.bz2
-            sudo mv bitcoin-${{ matrix.bitcoind-version }}/bin/* /usr/local/bin
-            rm -rf bitcoin-${{ matrix.bitcoind-version }}-x86_64-linux-gnu.tar.gz bitcoin-${{ matrix.bitcoind-version }}
 
         run: |
           PATH=/root/.local/bin:$PATH