chore: downgrade log severity level of 'not_ready' nodes to info

apps/emqx_conf/src/emqx_conf_app.erl

@@ -134,7 +134,7 @@ sync_cluster_conf2(Nodes) ->
                 msg => "ignored_nodes_when_sync_cluster_conf"
             },
             ?SLOG(warning, Warning);
-        true ->
+        true when Failed =/= [] ->
             %% There are core nodes running but no one was able to reply.
             ?SLOG(error, #{
                 msg => "failed_to_sync_cluster_conf",
@@ -142,6 +142,14 @@ sync_cluster_conf2(Nodes) ->
                 failed => Failed,
                 not_ready => NotReady
             });
+        true ->
+            %% There are core nodes booting up
+            ?SLOG(info, #{
+                msg => "peer_not_ready_for_config_sync",
+                reason => "The 'not_ready' peer node(s) are loading configs",
+                nodes => Nodes,
+                not_ready => NotReady
+            });
         false ->
             ok
     end,