The prayers you’re referring to are called the Leonine prayers after Pope Leo XIII, who asked they be recited after Low Mass for the intention of the whole Church. Later, Pope Pius XI requested they be said for the conversion of Russia. The prayers consisted of three Hail Marys, one Hail Holy Queen, a prayer to St. Michael the Archangel, and a three-fold invocation to the Sacred Heart.
These prayers were never part of the Roman Missal. The instruction to remove the prayers came before the Second Vatican Council closed in 1964.