Stop providing "ostree trivial-httpd" CLI

This follows upstream default behaviour. flatpak used to use it in its
tests, but the version in stable no longer does.

debian/rules

@@ -13,7 +13,6 @@ override_dh_autoreconf:
 
 configure_options = \
 	--enable-installed-tests \
-	--enable-trivial-httpd-cmdline \
 	--libexecdir='$${prefix}/lib' \
 	--with-dracut \
 	--with-grub2 \