xds: Remove InternalGrpcBootstrapperImpl.getJsonContent()

It has been unused since 84d30af.

Author: ejona86

xds/src/main/java/io/grpc/xds/InternalGrpcBootstrapperImpl.java

@@ -19,7 +19,6 @@
 import io.grpc.Internal;
 import io.grpc.xds.client.Bootstrapper.BootstrapInfo;
 import io.grpc.xds.client.XdsInitializationException;
-import java.io.IOException;
 import java.util.Map;
 
 /**
@@ -29,10 +28,6 @@
 public final class InternalGrpcBootstrapperImpl {
   private InternalGrpcBootstrapperImpl() {} // prevent instantiation
 
-  public static String getJsonContent() throws XdsInitializationException, IOException {
-    return new GrpcBootstrapperImpl().getJsonContent();
-  }
-
   public static BootstrapInfo parseBootstrap(Map<String, ?> bootstrap)
       throws XdsInitializationException {
     return new GrpcBootstrapperImpl().bootstrap(bootstrap);