[tests] Fix cctest/test-spaces/OldLargeObjectSpace

... which doesn't expect GCs caused by concurrent allocations.

Bug: v8:12779
Change-Id: I4ab13711ed4d98e7a46d759f0020b5983dec4ee0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3707278
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Omer Katz <omerkatz@chromium.org>
Auto-Submit: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81219}

test/cctest/heap/test-spaces.cc

@@ -336,6 +336,9 @@ TEST(OldLargeObjectSpace) {
   // incremental marker.
   FLAG_incremental_marking = false;
   FLAG_max_heap_size = 20;
+  // This test doesn't expect GCs caused by concurrent allocations in the
+  // background thread.
+  FLAG_stress_concurrent_allocation = false;
 
   OldLargeObjectSpace* lo = CcTest::heap()->lo_space();
   CHECK_NOT_NULL(lo);