Port filter out lower levels when syncing research

Fix the next level of an infinite research getting updated with the
progress of the previous level from other nodes in the cluster by
filtering out infinite researches with a lower level than the local
level.

This is a port of 075d54f.

sharedPlugins/researchSync/index.js

@@ -253,6 +253,12 @@ class ResearchSync {
 			}
             if (isNaN(cluster_techs[name].progress))
                 continue
+
+			// Do not update progress for infinite techs with a local level that's higher.
+			if (tech.infinite && tech.level > cluster_techs[name].level) {
+				continue;
+			}
+
             if (tech.progress < cluster_techs[name].progress)
                 result[name] = cluster_techs[name]
         }