ACID: remove any difference between an mm table insert and full acid table insert

HIVE-21164 makes acid insert work like mm-table insert by writing directly to the destination and using manifest files to track committed files in a task and the job. After that, while there should be no difference in the insert code paths, there may be some cases where the difference remains (e.g. HIVE-17695). This jira will investigate any such issues and fix it.