Millions of Americans will spend Memorial Day weekend honoring those who died while serving in the US military — but California congressional candidate Mai Vang likely will not be one of them. The lefty Sacramento city councilmember has boasted about refusing to say the Pledge of Allegiance at public meetings and ceremonies — and routinely turned her back on the flag. Vang, who is attempting to unseat longtime Democratic Rep. Doris Matsui in the June primary election, is currently polling neck-