Replace "Member" with "member"

The default Keystone bootstrap process adds "member" (lowercase "m"),
not "Member".
https://docs.openstack.org/keystone/latest/admin/case-insensitive.html#roles

Tempest was changed to have a lowercase default:
https://opendev.org/openstack/tempest/commit/99d4dae684
https://bugs.launchpad.net/tempest/+bug/1330132

This change does the same for rally-openstack.

Change-Id: I2b9877ac02d0d41927ff69c56e0812aa0cbbac94
Closes-Bug: #1884825

etc/rally/rally.conf.sample

@@ -752,7 +752,7 @@
 
 # Role required for users to be able to create Swift containers
 # (string value)
-#swift_operator_role = Member
+#swift_operator_role = member
 
 # User role that has reseller admin (string value)
 #swift_reseller_admin_role = ResellerAdmin

rally_openstack/common/cfg/tempest.py

@@ -41,7 +41,7 @@ OPTS = {"openstack": [
                     "itself if the values for the corresponding config "
                     "options are not specified in the Tempest config file"),
     cfg.StrOpt("swift_operator_role",
-               default="Member",
+               default="member",
                deprecated_group="tempest",
                help="Role required for users "
                     "to be able to create Swift containers"),

samples/tasks/scenarios/cinder/create-and-list-volume-backups.json

@@ -18,7 +18,7 @@
                     "tenants": 1,
                     "users_per_tenant": 1
                 },
-                "roles": ["Member"]
+                "roles": ["member"]
             },
             "sla": {
                 "failure_rate": {

samples/tasks/scenarios/cinder/create-and-list-volume-backups.yaml

@@ -16,7 +16,7 @@
           tenants: 1
           users_per_tenant: 1
         roles:
-          - "Member"
+          - "member"
       sla:
         failure_rate:
           max: 0

samples/tasks/scenarios/cinder/create-and-restore-volume-backup.json

@@ -17,7 +17,7 @@
                     "tenants": 1,
                     "users_per_tenant": 1
                 },
-                "roles": ["Member"]
+                "roles": ["member"]
             },
             "sla": {
                 "failure_rate": {

samples/tasks/scenarios/cinder/create-and-restore-volume-backup.yaml

@@ -15,7 +15,7 @@
           tenants: 1
           users_per_tenant: 1
         roles:
-          - "Member"
+          - "member"
       sla:
         failure_rate:
           max: 0

samples/tasks/scenarios/cinder/create-volume-backup.json

@@ -17,7 +17,7 @@
                     "tenants": 1,
                     "users_per_tenant": 1
                 },
-                "roles": ["Member"]
+                "roles": ["member"]
             },
             "sla": {
                 "failure_rate": {

samples/tasks/scenarios/cinder/create-volume-backup.yaml

@@ -15,7 +15,7 @@
           tenants: 1
           users_per_tenant: 1
         roles:
-          - "Member"
+          - "member"
       sla:
         failure_rate:
           max: 0