Only return from wait_for_chainlock when the block is actually proces…

…sed (#2728)

getblock also returns blocks which are not processed yet or in the middle
of processing.

qa/rpc-tests/llmq-chainlocks.py

@@ -102,7 +102,7 @@ def wait_for_chainlock(self, node, block_hash):
         while time() - t < 15:
             try:
                 block = node.getblock(block_hash)
-                if block["chainlock"]:
+                if block["confirmations"] > 0 and block["chainlock"]:
                     return
             except:
                 # block might not be on the node yet