Install Guide: Remove duplicate sentences
Install Guide: Remove duplicate sentences

The text for mysql_secure_installation was shown for os="opensuse;sles"
since it was on both paragraphs. Once is enough ;)

Change-Id: I1ffaa7faac55379d8bd78753aeff6e1f7e834519
Closes-Bug: 1245950
backport: havana

potsmaster/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,saeki-masaki/openstack-manuals,potsmaster/openstack-manuals,saeki-masaki/openstack-manuals,kairoaraujo/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,gongysh2004/openstack-manual,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,kairoaraujo/openstack-manuals