[SPARK-16632][SQL] Revert PR #14272: Respect Hive schema when merging parquet schema

## What changes were proposed in this pull request?

PR #14278 is a more general and simpler fix for SPARK-16632 than PR #14272. After merging #14278, we no longer need changes made in #14272. So here I revert them.

This PR targets both master and branch-2.0.

## How was this patch tested?

Existing tests.

Author: Cheng Lian <lian@databricks.com>

Closes #14300 from liancheng/revert-pr-14272.