change the download location of the ml native code build (#36733)

change the download location to load the custom binaries created in elastic/ml-cpp#344

Author: Hendrik Muhs

x-pack/plugin/ml/cpp-snapshot/build.gradle

@@ -9,7 +9,7 @@ ext.version = VersionProperties.elasticsearch
 // for this project so it can be used with dependency substitution.
 
 void getZip(File snapshotZip) {
-  String zipUrl = "http://prelert-artifacts.s3.amazonaws.com/maven/org/elasticsearch/ml/ml-cpp/${version}/ml-cpp-${version}.zip"
+  String zipUrl = "http://prelert-artifacts.s3.amazonaws.com/maven/org/elasticsearch/ml/ml-cpp-df/${version}/ml-cpp-df-${version}.zip"
   File snapshotMd5 = new File(snapshotZip.toString() + '.md5')
   HttpURLConnection conn = (HttpURLConnection) new URL(zipUrl).openConnection();