[MINOR] Fix mlcontext debug/trace logging (not in nn tests)

This patch fixes the recently enabled debug/trace logging in mlcontext
because the application tests timeout. Unfortunately, the nn tests
(in applications) inherit from the mlcontext tests and these nn tests
execute a log of tiny mini-batch operations where the log output is
just way too large.

src/test/java/org/apache/sysds/test/applications/nn/BaseTest.java

@@ -32,6 +32,11 @@ public abstract class BaseTest extends MLContextTestBase {
 
 	private static final String ERROR_STRING = "ERROR:";
 
+	public BaseTest() {
+		//disable debug and trace logging in mlcontext super class since
+		//the nn tests execute a lot of mini-batch operations
+		_enableTracing = false;
+	}
 
 	protected void run(String name) {
 		run(name, false);

src/test/java/org/apache/sysds/test/functions/mlcontext/MLContextTestBase.java

@@ -66,7 +66,8 @@ public abstract class MLContextTestBase extends AutomatedTestBase {
 	protected String testDir = null;
 	protected String testName = null;
 	protected Level _oldLevel = null;
-
+	protected boolean _enableTracing = true;
+
 	@Override
 	public void setUp() {
 		Class<? extends MLContextTestBase> clazz = this.getClass();
@@ -78,10 +79,12 @@ public void setUp() {
 
 		//run all mlcontext tests in loglevel trace to improve test coverage
 		//of all logging in various components
-		_oldLevel = Logger.getLogger("org.apache.sysds").getLevel();
-		Logger.getLogger("org.apache.sysds").setLevel( Level.TRACE );
+		if( _enableTracing ) {
+			_oldLevel = Logger.getLogger("org.apache.sysds").getLevel();
+			Logger.getLogger("org.apache.sysds").setLevel( Level.TRACE );
+		}
 	}
-
+	
 	@BeforeClass
 	public static void setUpClass() {
 		spark = createSystemDSSparkSession("SystemDS MLContext Test", "local");
@@ -93,7 +96,8 @@ public static void setUpClass() {
 	@Override
 	public void tearDown() {
 		super.tearDown();
-		Logger.getLogger("org.apache.sysds").setLevel( _oldLevel );
+		if(_enableTracing)
+			Logger.getLogger("org.apache.sysds").setLevel( _oldLevel );
 	}
 
 	@AfterClass