Update apt cache when updating packages

In order to get new packages available for installation apt cache should be updated.

Change-Id: I38e07586ab3d30c2689c91a65f1ffda47d5cffaf
Related-Prod: https://mirantis.jira.com/browse/PROD-29519
diff --git a/component-maintenance-update.groovy b/component-maintenance-update.groovy
index 1b7264d..5cd7fec 100644
--- a/component-maintenance-update.groovy
+++ b/component-maintenance-update.groovy
@@ -42,6 +42,8 @@
  */
 
 def installPkgUpdate(saltMaster, target, pkgs) {
+    common.infoMsg("Updating apt cache on ${target}")
+    runShCommand(saltMaster, target, 'apt update')
     common.infoMsg("Installing ${pkgs} updates on ${target}")
     runShCommand(saltMaster, target, "apt install --only-upgrade ${pkgs.join(' ')} -y")
 }