BUG/MINOR: cfgparse-global: remove tune.fast-forward from common_kw_list

BUG/MINOR: cfgparse-global: remove tune.fast-forward from common_kw_list

Remove tune.fast-forward from common_kw_list. It was replaced by
'tune.disable-fast-forward' and it's no longer present in "if..else if.."
parser from cfg_parse_global(). Otherwise, it may be shown as the best-match
keyword for some tune options, which is now wrong.

Should be backported in versions 2.9 and 3.0.

(cherry picked from commit 2e6e159ac47468b6b65e9678c9e4d1fe746165e8)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>