[SPARK-11423] remove MapPartitionsWithPreparationRDD

[davies]

Since we do not need to preserve a page before calling compute(), MapPartitionsWithPreparationRDD is not needed anymore.

This PR basically revert #8543, #8511, #8038, #8011

[SparkQA]

Test build #44692 has finished for PR 9381 at commit 374ec3b.

• This patch fails MiMa tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #1962 has finished for PR 9381 at commit fed4ab6.

• This patch fails MiMa tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #44696 has finished for PR 9381 at commit 258d275.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[yhuai]

Avoid of using mapPartitions can help us reduce the costs on closure cleaner. Should we create MapPartitionsRDD directly?

[davies]

@yhuai I just rollback the changes, we use mapPartitions a lot, they should not have much different.

[davies]

Since this PR just revert some patches, I will merge it to unblock #9383