Extend default update repos

  * Add percona|extra|saltstack repos to default one, as they always
    enabled at all nodes

Prod-related: PROD-23765 (PROD:23765)

Change-Id: Ib8be2d053caad80faf9eb183ddd46902176af435
(cherry picked from commit 9459cfdbec3024480c9f5da700099eb9d9f465ca)
diff --git a/linux/system/repo/mcp/apt_mirantis/update/init.yml b/linux/system/repo/mcp/apt_mirantis/update/init.yml
index 167f896..5897657 100644
--- a/linux/system/repo/mcp/apt_mirantis/update/init.yml
+++ b/linux/system/repo/mcp/apt_mirantis/update/init.yml
@@ -1,2 +1,5 @@
 classes:
+- system.linux.system.repo.mcp.apt_mirantis.update.extra
+- system.linux.system.repo.mcp.apt_mirantis.update.percona
+- system.linux.system.repo.mcp.apt_mirantis.update.saltstack
 - system.linux.system.repo.mcp.apt_mirantis.update.ubuntu