okhttp: revert "okhttp: Add restricted AppEngine SSL setup (#2795)"

This reverts commit b753231.

okhttp/src/main/java/io/grpc/okhttp/OkHttpChannelBuilder.java

@@ -53,16 +53,13 @@
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.security.GeneralSecurityException;
-import java.security.KeyStore;
-import java.security.SecureRandom;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 import javax.annotation.Nullable;
 import javax.net.ssl.SSLContext;
 import javax.net.ssl.SSLSocketFactory;
-import javax.net.ssl.TrustManagerFactory;
 
 /** Convenience class for building channels with the OkHttp transport. */
 @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1785")
@@ -255,25 +252,7 @@ SSLSocketFactory createSocketFactory() {
       case TLS:
         try {
           if (sslSocketFactory == null) {
-            SSLContext sslContext;
-            if (GrpcUtil.IS_RESTRICTED_APPENGINE) {
-              // The following auth code circumvents the following AccessControlException:
-              // access denied ("java.util.PropertyPermission" "javax.net.ssl.keyStore" "read")
-              // Conscrypt will attempt to load the default KeyStore if a trust manager is not
-              // provided, which is forbidden on AppEngine
-              sslContext = SSLContext.getInstance("TLS", Platform.get().getProvider());
-              TrustManagerFactory trustManagerFactory =
-                  TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
-              trustManagerFactory.init((KeyStore) null);
-              sslContext.init(
-                  null,
-                  trustManagerFactory.getTrustManagers(),
-                  // Use an algorithm that doesn't need /dev/urandom
-                  SecureRandom.getInstance("SHA1PRNG", Platform.get().getProvider()));
-
-            } else {
-              sslContext = SSLContext.getInstance("Default", Platform.get().getProvider());
-            }
+            SSLContext sslContext = SSLContext.getInstance("Default", Platform.get().getProvider());
             sslSocketFactory = sslContext.getSocketFactory();
           }
           return sslSocketFactory;