[SPARK-28178][SQL][followup] DataSourceV2: DataFrameWriter.insertInfo

[jzhuge]

What changes were proposed in this pull request?

• DataFrameWriter.insertInto should match column names by position.
• Clean up test cases.

How was this patch tested?

New tests:

• insertInto: append by position
• insertInto: overwrite partitioned table in static mode by position
• insertInto: overwrite partitioned table in dynamic mode by position

[SparkQA]

Test build #108629 has finished for PR 25353 at commit 7313f1e.

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

[dongjoon-hyun]

Hi, @jzhuge . HOTFIX is used when the branch is broken and all the PR builders are failed due to that.

[cloud-fan]

thanks, merging to master!