Conditionally disable :example-frontend-js for snapshot train

It doesn't work properly with new JS IR BE because it depends on a really old plugin version

settings.gradle

@@ -11,7 +11,8 @@ def module(String path) {
     include(name)
     project(":$name").projectDir = file(path)
 }
-
+def prop = properties['build_snapshot_train']
+ext.build_snapshot_train = prop != null && prop != ""
 // ---------------------------
 
 include('benchmarks')