Fix uint16 overflow bug in max vector

  size and add independent reader/writer
  verification tests

Author: vinooganesh

parquet-column/src/main/java/org/apache/parquet/column/values/alp/AlpConstants.java

@@ -59,8 +59,12 @@ private AlpConstants() {
   /** Log2 of the default vector size */
   public static final int DEFAULT_VECTOR_SIZE_LOG = 10;
 
-  /** Maximum allowed log2 of vector size */
-  static final int MAX_LOG_VECTOR_SIZE = 16;
+  /**
+   * Maximum allowed log2 of vector size.
+   * Capped at 15 (vectorSize=32768) because num_exceptions is uint16 (max 65535),
+   * so vectorSize must not exceed 65535 to avoid overflow when all values are exceptions.
+   */
+  static final int MAX_LOG_VECTOR_SIZE = 15;
 
   /** Minimum allowed log2 of vector size */
   static final int MIN_LOG_VECTOR_SIZE = 3;