Revert "Change getUnicodeStream encoding from UTF-8 to UTF-16."

This reverts commit d4d62e9.

To be consistent with PreparedStatement.setUnicodeStream which provides
UTF-8 encoding, ResultSet.getUnicodeStream has to also use the same
encoding. Changes in d4d62e9 were made under the influence of JDBC API
for getUnicodeStream that says 'a stream of two-byte 3 characters. The
first byte is the high byte; the second byte is the low byte'.

Author: nicktorwald

Diff for: src/main/java/org/tarantool/jdbc/SQLResultSet.java

@@ -336,7 +336,7 @@ public InputStream getAsciiStream(String columnLabel) throws SQLException {
     @Override
     public InputStream getUnicodeStream(int columnIndex) throws SQLException {
         String string = getString(columnIndex);
-        return string == null ? null : new ByteArrayInputStream(string.getBytes(Charset.forName("UTF-16")));
+        return string == null ? null : new ByteArrayInputStream(string.getBytes(Charset.forName("UTF-8")));
     }
 
     @Override