BUG/MINOR: cfgparse-global: clean common_kw_list

BUG/MINOR: cfgparse-global: clean common_kw_list

This patch fixes commits 118ac11ce
("MINOR: cfgparse-global: move mode's keywords in cfg_kw_list") and 83ff4db18
(MINOR: cfgparse-global: move no<poller_name> in cfg_kw_list).

'common_kw_list' serves to show the best-match keyword in cfg_parse_global(), if
the given keyword was not parsed in "if..else if.." cases. cfg_parse_global()
is still used as a parser for some keywords from the global section.

Mode-specific and no<poller_name> keywords now have their own parsers. They no
longer take place in the "if..else if.." from cfg_parse_global() and they are
registered in the 'cfg_kws' list. So, there is no longer need to duplicate
them in the 'common_kw_list'. Otherwise, they will be shown twice in parser
error message.