Switch to stable branch for system-config

Change-Id: I6a21e2c91dfc1c201351ad3c9ce980122c874b0f

murano-apps/SystemConfig/package/Classes/SystemConfig.yaml

@@ -19,6 +19,7 @@ Properties:
     Default: 'https://review.fuel-infra.org/open-paas/system-config'
   branchName:
     Contract: $.string()
+    Default: 'stable'
   patchId:
     Contract: $.string()
 Methods:

murano-apps/SystemConfig/package/UI/ui.yaml

@@ -32,6 +32,7 @@ Forms:
           initial: https://review.fuel-infra.org/open-paas/project-config
           required: true
         - name: branchName
+          initial: stable
           type: string
           label: Branch Name
           description: Provide branch, which should be used for for system-config repo.