meson: stop printing 'https' option twice in our summaries

The value for the 'https' backend option is printed twice: once via the
summary of auto-detected features and once via our summary of backends.
Drop it from the former summary.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

meson.build

@@ -2188,7 +2188,6 @@ summary({
   'expat': expat.found(),
   'gettext': intl.found(),
   'gitweb': gitweb_option.allowed(),
-  'https': https_backend,
   'iconv': iconv.found(),
   'pcre2': pcre2.found(),
   'perl': perl_features_enabled,