full_install_osm.sh: point to ReleaseSIX by default

Change-Id: I7cd931a72e14d617650a7241380c9d99e0e0cbd9
Signed-off-by: Gerardo García <gerardo-garcia@users.noreply.github.com>
(cherry picked from commit c471ecc4)

installers/full_install_osm.sh

@@ -1154,7 +1154,7 @@ SHOWOPTS=""
 COMMIT_ID=""
 ASSUME_YES=""
 INSTALL_FROM_SOURCE=""
-RELEASE="ReleaseFIVE"
+RELEASE="ReleaseSIX"
 REPOSITORY="stable"
 INSTALL_VIMEMU=""
 INSTALL_FROM_LXDIMAGES=""