Update platform version

Looks like the one we were using disappeared again.

Author: code-asher

gradle.properties

@@ -26,7 +26,7 @@ pluginUntilBuild=242.*
 # that exists, ideally the most recent one, for example
 # 233.15325-EAP-CANDIDATE-SNAPSHOT).
 platformType=GW
-platformVersion=233.15325-EAP-CANDIDATE-SNAPSHOT
+platformVersion=233.15619-EAP-CANDIDATE-SNAPSHOT
 instrumentationCompiler=242.19533-EAP-CANDIDATE-SNAPSHOT
 # Gateway does not have open sources.
 platformDownloadSources=true