Update haproxy backend checks for placement

Starting from Queens OPTIONS (default haproxy check method) is not allowed.
This patch updates placement.yml haproxy meta to expect both 401 - which was
default in Pike and 200 - default responce code in Queens. Also change
check method to GET.

Change-Id: Ieed01011df8c81476dc8d9fbb2cb2a63ef649639
Related-Prod: PROD-27155
2 files changed