Install percona pkg before updating mysql

Also change salt function call to allow downgrade mysql-common pkg.

DOCIMPACT: dist-upgrade for upgrade to 2019.2.18 is strictly preffered.

PROD-36814

Change-Id: I90ba8df3206611439ba42a8bfe61e1f433f9a342
(cherry picked from commit bf9af16f69aedb4a5c86342edcce8047ded07e5b)
diff --git a/galera/upgrade/update_master.sls b/galera/upgrade/update_master.sls
index 52d03e1..930bf90 100644
--- a/galera/upgrade/update_master.sls
+++ b/galera/upgrade/update_master.sls
@@ -11,9 +11,15 @@
   cmd.run:
   - name: "sed -i '/gcomm/c\\wsrep_cluster_address=\"gcomm://\"' /etc/mysql/my.cnf"
 
-galera_packages:
+percona_xtrabackup_24_package:
   pkg.latest:
-  - names: {{ galera.pkgs }}
+  - names:
+    - percona-xtrabackup-24
+
+galera_packages:
+  pkg.installed:
+    - version: latest
+    - pkgs: {{ galera.pkgs }}
 
 mysql_service_stopped:
   service.dead:
diff --git a/galera/upgrade/update_slave.sls b/galera/upgrade/update_slave.sls
index aa57616..8ed886e 100644
--- a/galera/upgrade/update_slave.sls
+++ b/galera/upgrade/update_slave.sls
@@ -7,6 +7,12 @@
     - name: "dump_message_update_slave"
     - text: "Running galera.upgrade.update_slave"
 
-galera_packages:
+percona_xtrabackup_24_package:
   pkg.latest:
-  - names: {{ galera.pkgs }}
+  - names:
+    - percona-xtrabackup-24
+
+galera_packages:
+  pkg.installed:
+    - version: latest
+    - pkgs: {{ galera.pkgs }}