Disable minor compactions when using query based compactor

HIVE-20699 introduces a new config, which can enable major compaction to be run as a HiveQL query, so that it can take advantage of the underlying execution engine and not run compaction as an MR job. This is particularly useful for cloud deployments. For now, we will disable minor compactions if this config flag is enabled. We will work on enabling minor compactions in HIVE-20934.