Fix a test case of 35chars+

Current test_delete_image_id_is_over_35_character_limit() tests
both non-hex and over 35 characters of image_id.
test_delete_image_id_is_over_35_character_limit() should test
only over 35 characters of image_id because of its name and comment.

Change-Id: Ie1674a540fa540f4d31edccbbeea293a1eb75e6d
Merge "Fix a test case of 35chars+"