Enable jdk-system-out Forbidden API checks on test sources

buildSrc/src/main/groovy/org/elasticsearch/gradle/precommit/PrecommitTasks.groovy

@@ -64,7 +64,7 @@ class PrecommitTasks {
         project.forbiddenApis {
             internalRuntimeForbidden = true
             failOnUnsupportedJava = false
-            bundledSignatures = ['jdk-unsafe', 'jdk-deprecated']
+            bundledSignatures = ['jdk-unsafe', 'jdk-deprecated', 'jdk-system-out']
             signaturesURLs = [getClass().getResource('/forbidden/jdk-signatures.txt'),
                               getClass().getResource('/forbidden/es-all-signatures.txt')]
             suppressAnnotations = ['**.SuppressForbidden']
@@ -72,7 +72,6 @@ class PrecommitTasks {
         Task mainForbidden = project.tasks.findByName('forbiddenApisMain')
         if (mainForbidden != null) {
             mainForbidden.configure {
-                bundledSignatures += 'jdk-system-out'
                 signaturesURLs += getClass().getResource('/forbidden/es-core-signatures.txt')
             }
         }

test/build.gradle

@@ -29,7 +29,6 @@ subprojects {
   
   // the main files are actually test files, so use the appropriate forbidden api sigs
   forbiddenApisMain {
-    bundledSignatures = ['jdk-unsafe', 'jdk-deprecated']
     signaturesURLs = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt'),
                       PrecommitTasks.getResource('/forbidden/es-signatures.txt'),
                       PrecommitTasks.getResource('/forbidden/es-test-signatures.txt')]

test/framework/build.gradle

@@ -38,7 +38,6 @@ compileTestJava.options.compilerArgs << '-Xlint:-rawtypes'
 
 // the main files are actually test files, so use the appropriate forbidden api sigs
 forbiddenApisMain {
-  bundledSignatures = ['jdk-unsafe', 'jdk-deprecated']
   signaturesURLs = [PrecommitTasks.getResource('/forbidden/all-signatures.txt'),
                     PrecommitTasks.getResource('/forbidden/test-signatures.txt')]
 }