Revert "server: BroadcastMessage will no longer block until completion"
Revert "server: BroadcastMessage will no longer block until completion"

This reverts commit 6db90ef09ab974df0ff09aeaf75a3d80414d4f50.

The root cause was fixed by commit
f4e7c36c80e8e2be9edb78b3b317c69d28d6d78f. As a result, this commit is no
longer needed.

aakselrod/lnd,aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd