[tf2tflite] Enable Placeholder_000 and Multiple_IO_002 (#4196)

[tf2tflite] Enable Placeholder_000 and Multiple_IO_002 (#4196)

Recent changes on moco-tf and exo-tflite resolve Placeholder_000 and
Multiple_IO_002 test failure.

- moco-tf now eliminates Forward by default, which resolves
Placeholder_000 failure.
- exo-tflite now honor the input/output order, which resolves
Multiple_IO_002 failure.

This commit updates tf2tflite test framework to check Multiple_IO_002
and Placeholder_000 by default to prevent regression.

Signed-off-by: Jonghyun Park <jh1302.park@samsung.com>