[UTest] Fix unit test assuming 4 KiB page size.

Fix the unit test of of `list_allocator`, which was incorrectly assuming
4 KiB pages. However, on macOS M1 (ARM architecture), we do have 16 KiB
pages. This fix adapts the pre-allocation to compute the amount of
memory based on the system's actual pagesize.

Author: alir3zakh

unittest/util/AllocatorTest.cpp

@@ -272,7 +272,7 @@ TEST_CASE("list_allocator", "[core][util][allocator]")
         SECTION("across pages, within allocations")
         {
             const auto pagesize = get_pagesize();
-            list_allocator B(64 * 1024);
+            list_allocator B(16 * pagesize);
             CHECK(B.num_chunks_available() == 1); // pre-allocation
 
             auto *p0 = B.allocate(2 * pagesize);