ci: Temporarily disable leak check in valgrind

```
==3052== 56 bytes in 1 blocks are possibly lost in loss record 1 of 1
  ==3052==    at 0x4E050C5: malloc (vg_replace_malloc.c:442)
  ==3052==    by 0x19FBF3: alloc (alloc.rs:99)
  ==3052==    by 0x19FBF3: alloc_impl (alloc.rs:192)
  ==3052==    by 0x19FBF3: allocate (alloc.rs:254)
  ==3052==    by 0x19FBF3: {closure#0}<std::thread::Inner> (sync.rs:483)
  ==3052==    by 0x19FBF3: allocate_for_layout<core::mem::maybe_uninit::MaybeUninit<std::thread::Inner>, alloc::sync::{impl#14}::new_uninit::{closure_env#0}<std::thread::Inner>, fn(*mut u8) -> *mut alloc::sync::ArcInner<core::mem::maybe_uninit::MaybeUninit<std::thread::Inner>>> (sync.rs:1925)
  ==3052==    by 0x19FBF3: new_uninit<std::thread::Inner> (sync.rs:481)
  ==3052==    by 0x19FBF3: new_inner (mod.rs:1341)
  ==3052==    by 0x19FBF3: new_main (mod.rs:1331)
  ==3052==    by 0x19FBF3: init (rt.rs:106)
  ==3052==    by 0x19FBF3: {closure#0} (rt.rs:157)
  ==3052==    by 0x19FBF3: do_call<std::rt::lang_start_internal::{closure_env#0}, ()> (panicking.rs:557)
  ==3052==    by 0x19FBF3: try<(), std::rt::lang_start_internal::{closure_env#0}> (panicking.rs:520)
  ==3052==    by 0x19FBF3: catch_unwind<std::rt::lang_start_internal::{closure_env#0}, ()> (panic.rs:358)
  ==3052==    by 0x19FBF3: std::rt::lang_start_internal (rt.rs:157)
  ==3052==    by 0x13BF49: std::rt::lang_start (rt.rs:179)
  ==3052==    by 0x13C06D: main (in /home/runner/work/portable-atomic/portable-atomic/target/debug/deps/portable_atomic_util-8f64e7913de06efb)
  ==3052==
  ==3052== LEAK SUMMARY:
  ==3052==    definitely lost: 0 bytes in 0 blocks
  ==3052==    indirectly lost: 0 bytes in 0 blocks
  ==3052==      possibly lost: 56 bytes in 1 blocks
  ==3052==    still reachable: 0 bytes in 0 blocks
  ==3052==         suppressed: 0 bytes in 0 blocks
```

tools/test.sh

@@ -238,7 +238,9 @@ case "${cmd}" in
         exit 0
         ;;
     valgrind)
-        export "CARGO_TARGET_${target_upper}_RUNNER"="valgrind -v --error-exitcode=1 --error-limit=no --leak-check=full --show-leak-kinds=all --track-origins=yes --fair-sched=yes"
+        # TODO: upstream bug
+        # export "CARGO_TARGET_${target_upper}_RUNNER"="valgrind -v --error-exitcode=1 --error-limit=no --leak-check=full --show-leak-kinds=all --track-origins=yes --fair-sched=yes"
+        export "CARGO_TARGET_${target_upper}_RUNNER"="valgrind -v --error-exitcode=1 --error-limit=no --leak-check=no --track-origins=yes --fair-sched=yes"
         # TODO: always pass randomize-layout
         export RUSTFLAGS="${RUSTFLAGS:-} --cfg valgrind"
         export RUSTDOCFLAGS="${RUSTDOCFLAGS:-} --cfg valgrind"