[SPARK-7320] [SQL] [Minor] Move the testData into beforeAll()

Follow up of #6340, to avoid the test report missing once it fails.

Author: Cheng Hao <hao.cheng@intel.com>

Closes #6312 from chenghao-intel/rollup_minor and squashes the following commits:

b03a25f [Cheng Hao] simplify the testData instantiation
09b7e8b [Cheng Hao] move the testData into beforeAll()