Remove hardcoded ssh key parameter

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

Change-Id: I5f0a3563d0c5f1842e515d287fbdfdb08360de7e
diff --git a/metadata/service/server/single.yml b/metadata/service/server/single.yml
index ea49766..ce430b4 100644
--- a/metadata/service/server/single.yml
+++ b/metadata/service/server/single.yml
@@ -1,8 +1,6 @@
 applications:
 - xtrabackup
 parameters:
-  _param:
-    xtrabackup_public_key: ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCzLUiHKAjfFXiZ3fsgx35uXF6VivfC5WFafu4QMalxmj6W+s277oCfdWA8Du5f1wtQXM73VQ5nHkXhM2UIfUMarsyhXK+BxKVrcgEBNHdKlDytaecUPyuOxTDdGWhN/DPv5/vL8NYWweEYBbNbLgU0Td7Rvm52TUXKThIDjeF7XDxX4ShXWipBSwU4boOUBtR8KWfga8fsqeBN+eacuAQFR3MrrOfVvAuWW6Bsf047cmd+V6Qv0raoW73Nu4M/ZAdTsaR5k62a0cHsSRoi3hCmNRqw+CZaQi8prQU6t26eWPEtznjp5EkPF+LLh8LxUoCfWqWT+Lxe8QQwT1nx/LCN
   xtrabackup:
     server:
       enabled: true