[SPARK-15094][SPARK-14803][SQL] Remove extra Project added in EliminateSerialization

## What changes were proposed in this pull request?

We will eliminate the pair of `DeserializeToObject` and `SerializeFromObject` in `Optimizer` and add extra `Project`. However, when DeserializeToObject's outputObjectType is ObjectType and its cls can't be processed by unsafe project, it will be failed.

To fix it, we can simply remove the extra `Project` and replace the output attribute of `DeserializeToObject` in another rule.

## How was this patch tested?
`DatasetSuite`.

Author: Liang-Chi Hsieh <simonh@tw.ibm.com>

Closes #12926 from viirya/fix-eliminate-serialization-projection.