Add params from backupninja and xtrabackup formulas

Related: PROD-27135 (PROD:27135)
Related: PROD-27147 (PROD:27147)
Related: PROD-27540 (PROD:27540)

Change-Id: I3b2e6d675c83e2a27b437199a6d06edb645106ca
diff --git a/backupninja/server/single.yml b/backupninja/server/single.yml
index 9897a6c..ac008d5 100644
--- a/backupninja/server/single.yml
+++ b/backupninja/server/single.yml
@@ -1,2 +1,9 @@
 classes:
 - service.backupninja.server.single
+parameters:
+  backupninja:
+    server:
+      home_dir: /srv/volumes/backup/backupninja
+      key:
+        backupninja_pub_key:
+          key: ${_param:backupninja_public_key}
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