Build: Fix client jars for plugins/modules to have the correct artifactId

For transport client plugins, the jars and poms are renamed with the
-client suffix. But we need the artifactId to match the id in the
filename.

buildSrc/src/main/groovy/org/elasticsearch/gradle/plugin/PluginBuildPlugin.groovy

@@ -57,7 +57,7 @@ public class PluginBuildPlugin extends BuildPlugin {
                 // file to a new name, copy the nebula generated pom to the same name,
                 // and generate a different pom for the zip
                 project.signArchives.enabled = false
-                addJarPomGeneration(project)
+                addClientJarPomGeneration(project)
                 addClientJarTask(project)
                 if (isModule == false) {
                     addZipPomGeneration(project)
@@ -192,13 +192,14 @@ public class PluginBuildPlugin extends BuildPlugin {
     }
 
     /** Adds nebula publishing task to generate a pom file for the plugin. */
-    protected static void addJarPomGeneration(Project project) {
+    protected static void addClientJarPomGeneration(Project project) {
         project.plugins.apply(MavenPublishPlugin.class)
 
         project.publishing {
             publications {
                 jar(MavenPublication) {
                     from project.components.java
+                    artifactId = artifactId + '-client'
                     pom.withXml { XmlProvider xml ->
                         Node root = xml.asNode()
                         root.appendNode('name', project.pluginProperties.extension.name)