provision/downburst: drop redhat-lsb-core requirement for centos

This package cannot be found, and in fact it's not required,
because better use /etc/os-release

Signed-off-by: Kyr Shatskyy <kyrylo.shatskyy@clyso.com>

Author: Kyr Shatskyy

teuthology/provision/downburst.py

@@ -256,13 +256,11 @@ def build_config(self):
             ])
 
         # On CentOS/RHEL/Fedora, write the correct mac address and
-        # install redhab-lsb-core for `lsb_release`
         if os_type in ['centos', 'rhel', 'fedora']:
             user_info['runcmd'].extend([
                 ['sed', '-ie', 's/HWADDR=".*"/HWADDR="%s"/' % mac_address,
                  '/etc/sysconfig/network-scripts/ifcfg-eth0'],
             ])
-            user_info['packages'].append('redhat-lsb-core')
         # On Ubuntu, starting with 16.04, and Fedora, starting with 24, we need
         # to install 'python' to get python2.7, which ansible needs
         if os_type in ('ubuntu', 'fedora'):