Fix server group schema for compute microversion 2.64

For Compute microversion 2.64:
1. change policies to policy in:
   * GET /os-server-groups
   * POST /os-server-groups
   * GET /os-server-groups/{server_group_id}
2. add rules in:
   * GET /os-server-groups
   * POST /os-server-groups
   * GET /os-server-groups/{server_group_id}
3. remove metadata from:
   * GET /os-server-groups
   * POST /os-server-groups
   * GET /os-server-groups/{server_group_id}

The testcases of create_server_group should also be modified.

Co-authored-by: Ghanshyam Mann <gmann@ghanshyammann.com>

Change-Id: I8fc37415c968eb64380b8bd66b713aa6b733578f
6 files changed