[SPARK-23020] Ignore Flaky Test: SparkLauncherSuite.testInProcessLaun…

…cher

## What changes were proposed in this pull request?

Temporarily ignoring flaky test `SparkLauncherSuite.testInProcessLauncher` to de-flake the builds. This should be re-enabled when SPARK-23020 is merged.

## How was this patch tested?

N/A (Test Only Change)

Author: Sameer Agarwal <sameerag@apache.org>

Closes #20291 from sameeragarwal/disable-test-2.

core/src/test/java/org/apache/spark/launcher/SparkLauncherSuite.java

@@ -25,6 +25,7 @@
 import java.util.Properties;
 import java.util.concurrent.TimeUnit;
 
+import org.junit.Ignore;
 import org.junit.Test;
 import static org.junit.Assert.*;
 import static org.junit.Assume.*;
@@ -120,7 +121,8 @@ public void testChildProcLauncher() throws Exception {
     assertEquals(0, app.waitFor());
   }
 
-  @Test
+  // TODO: [SPARK-23020] Re-enable this
+  @Ignore
   public void testInProcessLauncher() throws Exception {
     // Because this test runs SparkLauncher in process and in client mode, it pollutes the system
     // properties, and that can cause test failures down the test pipeline. So restore the original