src: revert IS_RELEASE

PR-URL: #48505
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Ruy Adorno <ruyadorno@google.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Geoffrey Booth <webadmin@geoffreybooth.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>