Remove security manager policy files (elastic#127727)

Now that security manager is gone, the policy files are no longer
needed. This commit removes the server, test and plugin specific policy
files

Author: rjernst

build-tools/src/main/java/org/elasticsearch/gradle/plugin/BasePluginBuildPlugin.java

@@ -183,11 +183,7 @@ private static CopySpec createBundleSpec(
     ) {
         var bundleSpec = project.copySpec();
         bundleSpec.from(buildProperties);
-        bundleSpec.from(pluginMetadata, copySpec -> {
-            // metadata (eg custom security policy)
-            // the codebases properties file is only for tests and not needed in production
-            copySpec.exclude("plugin-security.codebases");
-        });
+        bundleSpec.from(pluginMetadata);
         bundleSpec.from(
             (Callable<TaskProvider<Task>>) () -> project.getPluginManager().hasPlugin("com.gradleup.shadow")
                 ? project.getTasks().named("shadowJar")

distribution/archives/integ-test-zip/src/javaRestTest/resources/plugin-security.policy

@@ -922,7 +922,7 @@ void jarHellCheck(PluginDescriptor candidateInfo, Path candidateDir, Path plugin
     private PluginDescriptor installPlugin(InstallablePlugin descriptor, Path tmpRoot, List<Path> deleteOnFailure) throws Exception {
         final PluginDescriptor info = loadPluginInfo(tmpRoot);
 
-        Path legacyPolicyFile = tmpRoot.resolve(PluginDescriptor.ES_PLUGIN_POLICY);
+        Path legacyPolicyFile = tmpRoot.resolve("plugin-security.policy");
         if (Files.exists(legacyPolicyFile)) {
             terminal.errorPrintln(
                 "WARNING: this plugin contains a legacy Security Policy file. Starting with version 8.18, "