Remove JSch threading hack

Remove the hack that allows us to use JSch with Java 7 on App Engine -
basically, we have a modified version of JSch that lets us attach a
GAE-friendly thread factory and use that for all JSch threads.

TESTED: Verified that RDE SFTP uploads still work on alpha.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=182208225

java/google/registry/rde/JSchModule.java

@@ -16,7 +16,6 @@ package google.registry.rde;
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
-import com.google.appengine.api.ThreadManager;
 import com.jcraft.jsch.JSch;
 import com.jcraft.jsch.JSchException;
 import dagger.Module;
@@ -33,7 +32,6 @@ public final class JSchModule {
       @Config("rdeSshIdentity") String identity,
       @Key("rdeSshClientPrivateKey") String privateKey,
       @Key("rdeSshClientPublicKey") String publicKey) {
-    applyAppEngineKludge();
     JSch jsch = new JSch();
     try {
       jsch.addIdentity(
@@ -48,14 +46,4 @@ public final class JSchModule {
     JSch.setConfig("StrictHostKeyChecking", "no");
     return jsch;
   }
-
-  /**
-   * Overrides the threadFactory used in JSch and disable {@link Thread#setName(String)} in order to
-   * ensure GAE compatibility. By default it uses the default executor, which fails under GAE. This
-   * is currently a Google-specific patch that needs to be sent upstream.
-   */
-  private static void applyAppEngineKludge() {
-    JSch.threadFactory = ThreadManager.currentRequestThreadFactory();
-    JSch.useThreadNames = false;
-  }
 }