test: add block sync to getblockfrompeer.py

This fixes an intermittent error, caused by blocks arriving
out of order due to how compact block relay may revert to headers
processing when the tip hasn't caught up, and resulting in slightly
different pruning behavior.

Making sure that all blocks from the previous tests are synced before
generating more blocks makes this impossible.
See Issue bitcoin#27749 for more details.

test/functional/rpc_getblockfrompeer.py

@@ -117,9 +117,11 @@ def run_test(self):
         assert_raises_rpc_error(-1, error_msg, self.nodes[1].getblockfrompeer, blockhash, node1_interface_id)
 
         self.log.info("Connect pruned node")
-        # We need to generate more blocks to be able to prune
         self.connect_nodes(0, 2)
         pruned_node = self.nodes[2]
+        self.sync_blocks([self.nodes[0], pruned_node])
+
+        # We need to generate more blocks to be able to prune
         self.generate(self.nodes[0], 400, sync_fun=self.no_op)
         self.sync_blocks([self.nodes[0], pruned_node])
         pruneheight = pruned_node.pruneblockchain(300)