[rally] remove deprecated arg

`name_length` is deprecated in latest rally due to changes related to
improvement of cleanup mechanism.

Change-Id: I636dcfe8d0a05f9b621e15d5ec302f74cc6d741a
Closes-Bug: #1507752

rally-jobs/keystone.yaml

@@ -2,8 +2,6 @@
 
   KeystoneBasic.create_user:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 100
@@ -14,8 +12,6 @@
 
   KeystoneBasic.create_delete_user:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 100
@@ -26,8 +22,6 @@
 
   KeystoneBasic.create_and_list_users:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 100
@@ -39,7 +33,6 @@
   KeystoneBasic.create_user_update_password:
     -
       args:
-        name_length: 10
         password_length: 10
       runner:
         type: "constant"
@@ -51,8 +44,6 @@
 
   KeystoneBasic.create_and_list_tenants:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 100
@@ -111,8 +102,6 @@
 
   KeystoneBasic.create_tenant:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 50
@@ -124,7 +113,6 @@
   KeystoneBasic.create_tenant_with_users:
     -
       args:
-        name_length: 10
         users_per_tenant: 10
       runner:
         type: "constant"
@@ -136,8 +124,6 @@
 
   KeystoneBasic.create_update_and_delete_tenant:
     -
-      args:
-        name_length: 10
       runner:
         type: "constant"
         times: 50