Do not upgrade packages with cloud-init

This patch deletes 'package_upgrade: true' option from cloud-init confs.
It caused upgrading of all the packages in the images spawned by murano.
This made spawning VMs slow and in certain cases caused
dpkg locks be still in place when murano-agent attempted to
install packages

Change-Id: I440d2985f9122dad53c81b15148e60df4e7e9583
Closes-Bug: 1548857

meta/io.murano/Resources/conflang.conf

@@ -21,8 +21,6 @@ yum_repos:
         gpgcheck: false
 
 
-package_upgrade: true
-
 packages:
  - chef
  - puppet

meta/io.murano/Resources/murano-init.conf

@@ -6,8 +6,6 @@
             gpgcheck: false
             name: Extra Packages for Enterprise Linux  - Testing
 
-    package_upgrade: true
-
     packages:
         - subversion
         - git-core