Silence byte-compiler using with-no-warnings in tests

Silence byte-compiler using with-no-warnings in tests

We could silence the specific warnings by adding support for them to
with-suppressed-warnings, but it is almost not worth the complexity
for warnings that only show up in one file.  In any case, it is not
urgent, so leave behind FIXMEs for now.

* test/lisp/emacs-lisp/eieio-tests/eieio-tests.el
(eieio-test-37-obsolete-name-in-constructor, class-c)
(eieio-test-01-mix-alloc-initarg, slotattr-class-base):
* test/lisp/progmodes/elisp-mode-tests.el
(xref-elisp-generic-co-located-default): Silence byte-compiler.