Initialize bitfield in Map with relaxed store

Need to use relaxed store for initializing bit_field. The concurrent marker accesses the has_prototype_slot bit in Map::bit_field to calculate header size.

Bug: v8:10315
Change-Id: I1eebd4a6f42b9263de7e424957b32884f7b910ad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2193712
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67710}

src/heap/factory.cc

@@ -1437,7 +1437,7 @@ Map Factory::InitializeMap(Map map, InstanceType type, int instance_size,
   // Must be called only after |instance_type|, |instance_size| and
   // |layout_descriptor| are set.
   map.set_visitor_id(Map::GetVisitorId(map));
-  map.set_bit_field(0);
+  map.set_relaxed_bit_field(0);
   map.set_bit_field2(Map::Bits2::NewTargetIsBaseBit::encode(true));
   int bit_field3 =
       Map::Bits3::EnumLengthBits::encode(kInvalidEnumCacheSentinel) |