autoware_auto_avp_demo: change euclidean cluster param for MS2

Description

Change side_length param for euclidean_cluster to fix #542 (closed)

Notes for Reviewer

Please check the vehicle is not covered by bounding boxes in LGSVL parking lot. It is going to be like this with side_length = 0.7 as I posetd.

Note: The default parameter is still old. Let me know if it is also needed.

Checklist