Fix `lsh` warning shortcomings (bug#56641)

Fix `lsh` warning shortcomings (bug#56641)

Reported by Basil Contovounesios.

* etc/NEWS: Mention how to suppress the warning.
* lisp/emacs-lisp/byte-run.el (with-suppressed-warnings): Amend doc string.
* lisp/subr.el: Use `macroexp-warn-and-return` to delay the warning
until codegen time (which makes it suppressible) and to prevent
repeated warnings.
* test/lisp/international/ccl-tests.el (shift):
* test/src/data-tests.el (data-tests-ash-lsh):
Suppress warning in tests of `lsh` itself.