MDEV-18841: /var/run -> /run for apparmor/systemd service

Match 10.5 path changes in:
 * b2feb030
 * aaaf005c
 * bb847777

support-files/mariadb@.service.in

@@ -100,7 +100,7 @@
 # in configuration between instances.
 #
 #   [Service]
-#   Environment=MYSQLD_MULTI_INSTANCE="--socket=/var/run/mysqld/%I.sock \
+#   Environment=MYSQLD_MULTI_INSTANCE="--socket=/run/mysqld/%I.sock \
 #                        --datadir=/var/lib/mysqld-multi/%I \
 #                        --skip-networking"
 #

support-files/policy/apparmor/usr.sbin.mysqld

@@ -54,8 +54,8 @@
   /var/log/mysql.log rw,
   /var/log/mysql/ r,
   /var/log/mysql/* rw,
-  /var/run/mysqld/mysqld.pid w,
-  /var/run/mysqld/mysqld.sock w,
+  /run/mysqld/mysqld.pid w,
+  /run/mysqld/mysqld.sock w,
 
 
   profile /bin/dash flags=(complain) {