registry-token-server has been updated to support POST method.
But for upgrade case(stx3.0 upgrade to stx4.0), containerd need
talk with old registry-token-server which doesn't support POST
method, and 400 error code will be returned. For this case,
containerd still need fallback to GET method.
Story: 2006145
Task: 38763
Change-Id: I9834d1afae406c7e1f80bea6034931d854d4e868
Signed-off-by: Shuicheng Lin <shuicheng.lin@intel.com>
0e1ad4bbcd