test: temporarily ignore sanitizer warning about blocked ptrace()

test: temporarily ignore sanitizer warning about blocked ptrace()

LLVM 22 introduced an additional check [0] for ptrace() syscall when
invoking sanitizers [0] which currently produces a false-positive
warning when running some of our units under sanitizers:

[   47.524680] systemd-timedated[740]: ==740==WARNING: ptrace appears to be blocked (is seccomp enabled?). LeakSanitizer may hang.
[   47.524680] systemd-timedated[740]: ==740==Child exited with signal 15.
...
[ 1555.734223] systemd-oomd[93]: ==93==WARNING: ptrace appears to be blocked (is seccomp enabled?). LeakSanitizer may hang.
[ 1555.734223] systemd-oomd[93]: ==93==Child exited with signal 15.
...

It is a false positive because we disable the seccomp filters
system-wide for our units in the sanitizer jobs.

Now, from what I've seen so far this happens only in
Type=notify(-reload) units that also utilize bus_event_loop_with_idle().
This, combined with the fact that the ptrace()-check child process from
[0] checks only if the child process was killed by _any_ signal, means
that if the systemd unit exits on its own after becoming idle and then
something sends it SIGTERM (either via explicit `systemctl stop` or
during system shutdown), this SIGTERM might hit the ptrace()-check child
process from the sanitizer handler (as we also send the signal to all
processes in the target cgroup), which the parent process then
mistakenly evaluates as a blocked ptrace() syscall, even though the
check process wasn't killed by SIGSYS.

I filed this as [1] to the LLVM project, but let's also temporarily
ignore the warning in the sanitizer report processing, as it currently
causes annoying test fails.

[0] https://github.com/llvm/llvm-project/commit/a708b4bf21d7c2298224cdacf7d424abc3c8fed4
[1] https://github.com/llvm/llvm-project/issues/193714