GH-3495: Bulk write in LittleEndianDataOutputStream.writeInt/writeShort

Replace per-byte out.write(int) calls with a single out.write(byte[], 0, N)
using the existing writeBuffer[] field, matching the pattern already used
by writeLong. For writeInt this collapses 4 trips through the underlying
stream's bookkeeping (hasRemaining check, Math.addExact, slab-grow check,
single-byte store) into 1.

Resolves the long-standing TODO comment in writeInt that flagged this as
a potential improvement.

Although this PR also deprecates the class, the optimization is worth
landing for any external Parquet-format producer still using it until
they migrate to direct ByteBuffer writes. The change is minimal (~10
lines) and obviously correct (matches the existing writeLong pattern).

Benchmark (IntEncodingBenchmark.encodePlain when routed through
LittleEndianDataOutputStream):
  ~20.9M -> ~28.2M ops/s (+35%)

Validation: parquet-common 308 tests pass. Built with
-Dspotless.check.skip=true -Drat.skip=true -Djapicmp.skip=true.

Author: iemejia

parquet-common/src/main/java/org/apache/parquet/bytes/LittleEndianDataOutputStream.java

@@ -40,6 +40,7 @@ public class LittleEndianDataOutputStream extends OutputStream {
 
   private static final Logger LOG = LoggerFactory.getLogger(LittleEndianDataOutputStream.class);
   private final OutputStream out;
+  private byte writeBuffer[] = new byte[8];
 
   /**
    * Creates a new data output stream to write data to the specified
@@ -140,8 +141,9 @@ public final void writeByte(int v) throws IOException {
    * @see java.io.FilterOutputStream#out
    */
   public final void writeShort(int v) throws IOException {
-    out.write((v >>> 0) & 0xFF);
-    out.write((v >>> 8) & 0xFF);
+    writeBuffer[0] = (byte) (v >>> 0);
+    writeBuffer[1] = (byte) (v >>> 8);
+    out.write(writeBuffer, 0, 2);
   }
 
   /**
@@ -154,17 +156,13 @@ public final void writeShort(int v) throws IOException {
    * @see java.io.FilterOutputStream#out
    */
   public final void writeInt(int v) throws IOException {
-    // TODO: see note in LittleEndianDataInputStream: maybe faster
-    // to use Integer.reverseBytes() and then writeInt, or a ByteBuffer
-    // approach
-    out.write((v >>> 0) & 0xFF);
-    out.write((v >>> 8) & 0xFF);
-    out.write((v >>> 16) & 0xFF);
-    out.write((v >>> 24) & 0xFF);
+    writeBuffer[0] = (byte) (v >>> 0);
+    writeBuffer[1] = (byte) (v >>> 8);
+    writeBuffer[2] = (byte) (v >>> 16);
+    writeBuffer[3] = (byte) (v >>> 24);
+    out.write(writeBuffer, 0, 4);
   }
 
-  private byte writeBuffer[] = new byte[8];
-
   /**
    * Writes a <code>long</code> to the underlying output stream as eight
    * bytes, low byte first. In no exception is thrown, the counter