Fix some toString methods in presto-orc (#23750)

Summary: Pull Request resolved: #23750

Differential Revision: D63643493

Author: sdruzkin

presto-orc/src/main/java/com/facebook/presto/orc/ChunkedSliceOutput.java

@@ -303,9 +303,9 @@ public String toString(Charset charset)
     @Override
     public String toString()
     {
-        StringBuilder builder = new StringBuilder("OutputStreamSliceOutputAdapter{");
+        StringBuilder builder = new StringBuilder("ChunkedSliceOutput{");
         builder.append("position=").append(size());
-        builder.append("bufferSize=").append(slice.length());
+        builder.append(", bufferSize=").append(slice.length());
         builder.append('}');
         return builder.toString();
     }

presto-orc/src/main/java/com/facebook/presto/orc/OrcOutputBuffer.java

@@ -423,9 +423,9 @@ public String toString(Charset charset)
     @Override
     public String toString()
     {
-        StringBuilder builder = new StringBuilder("OutputStreamSliceOutputAdapter{");
+        StringBuilder builder = new StringBuilder("OrcOutputBuffer{");
         builder.append("outputStream=").append(compressedOutputStream);
-        builder.append("bufferSize=").append(slice.length());
+        builder.append(", bufferSize=").append(slice.length());
         builder.append('}');
         return builder.toString();
     }