[test] Make two sanitize-coverage tests pass with glibc 2.39+

glibc 2.39 added `nonnull` attribute to most libio functions accepting a
`FILE*` parameter, including fprintf[1]. The -fsanitize=undefined mode
checks the argument to fprintf and has extra counters, not expected by
two tests. Specify -fno-sanitize=nonnull-attribute to make the two tests
pass.

Fix #82883

[1]: https://sourceware.org/git/?p=glibc.git;a=commit;h=64b1a44183a3094672ed304532bedb9acc707554

Pull Request: https://github.com/llvm/llvm-project/pull/84231