Build: Remove exclusions hack used for gradle 2.13 (#23809)

Now that we are on gradle 3.3, we can take advantage of a fix that was
made in 2.14 which properly handles disabling transitive dependencies in
pom generation.  As it was currently, we actually ended up generated two
exclusions sections in the generated pom. This is yet another example of
why we need validation on the pom files with our generation here, but I
leave that for another day because I still don't know a good way to do
it.

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -328,46 +328,15 @@ class BuildPlugin implements Plugin<Project> {
                 return
             }
 
-            // check each dependency for any transitive deps
+            // fix deps incorrectly marked as runtime back to compile time deps
+            // see https://discuss.gradle.org/t/maven-publish-plugin-generated-pom-making-dependency-scope-runtime/7494/4
             for (Node depNode : depsNodes.get(0).children()) {
-                String groupId = depNode.get('groupId').get(0).text()
-                String artifactId = depNode.get('artifactId').get(0).text()
-                String version = depNode.get('version').get(0).text()
-
-                // fix deps incorrectly marked as runtime back to compile time deps
-                // see https://discuss.gradle.org/t/maven-publish-plugin-generated-pom-making-dependency-scope-runtime/7494/4
                 boolean isCompileDep = project.configurations.compile.allDependencies.find { dep ->
                     dep.name == depNode.artifactId.text()
                 }
                 if (depNode.scope.text() == 'runtime' && isCompileDep) {
                     depNode.scope*.value = 'compile'
                 }
-
-                // collect the transitive deps now that we know what this dependency is
-                String depConfig = transitiveDepConfigName(groupId, artifactId, version)
-                Configuration configuration = project.configurations.findByName(depConfig)
-                if (configuration == null) {
-                    continue // we did not make this dep non-transitive
-                }
-                Set<ResolvedArtifact> artifacts = configuration.resolvedConfiguration.resolvedArtifacts
-                if (artifacts.size() <= 1) {
-                    // this dep has no transitive deps (or the only artifact is itself)
-                    continue
-                }
-
-                // we now know we have something to exclude, so add exclusions for all artifacts except the main one
-                Node exclusions = depNode.appendNode('exclusions')
-                for (ResolvedArtifact artifact : artifacts) {
-                    ModuleVersionIdentifier moduleVersionIdentifier = artifact.moduleVersion.id;
-                    String depGroupId = moduleVersionIdentifier.group
-                    String depArtifactId = moduleVersionIdentifier.name
-                    // add exclusions for all artifacts except the main one
-                    if (depGroupId != groupId || depArtifactId != artifactId) {
-                        Node exclusion = exclusions.appendNode('exclusion')
-                        exclusion.appendNode('groupId', depGroupId)
-                        exclusion.appendNode('artifactId', depArtifactId)
-                    }
-                }
             }
         }
     }