ensure yaml tests have correct length

Author: markjhoy

x-pack/plugin/src/yamlRestTest/resources/rest-api-spec/test/service_accounts/10_basic.yml

@@ -24,7 +24,7 @@ teardown:
 "Test get service accounts":
   - do:
       security.get_service_accounts: {}
-  - length: { '': 5 }
+  - length: { '': 4 }
   - is_true: "elastic/auto-ops"
   - is_true: "elastic/fleet-server"
   - is_true: "elastic/fleet-server-remote"
@@ -33,7 +33,7 @@ teardown:
   - do:
       security.get_service_accounts:
         namespace: elastic
-  - length: { '': 5 }
+  - length: { '': 4 }
   - is_true: "elastic/auto-ops"
   - is_true: "elastic/fleet-server"
   - is_true: "elastic/fleet-server-remote"