[Temporal] Fix GCC >= comparison error by cl/3624980.

Change kUTCTimeZoneIndex to int32_t from uint32_t
And compare index against 0.

Bug: v8:11544
Change-Id: Ib7dd55cab796d1d9a4b0e2869b098520265a04f0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3632678
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80412}

src/objects/js-temporal-objects.cc

@@ -1018,7 +1018,7 @@ MaybeHandle<JSTemporalTimeZone> CreateTemporalTimeZone(
   }
 #ifdef V8_INTL_SUPPORT
   int32_t time_zone_index = Intl::GetTimeZoneIndex(isolate, identifier);
-  if (time_zone_index >= JSTemporalTimeZone::kUTCTimeZoneIndex) {
+  if (time_zone_index >= 0) {
     return CreateTemporalTimeZoneFromIndex(isolate, target, new_target,
                                            time_zone_index);
   }

src/objects/js-temporal-objects.h

@@ -445,7 +445,7 @@ class JSTemporalTimeZone
   DECLARE_TEMPORAL_INLINE_GETTER_SETTER(offset_sub_milliseconds)
 
   int32_t time_zone_index() const;
-  static constexpr uint32_t kUTCTimeZoneIndex = 0;
+  static constexpr int32_t kUTCTimeZoneIndex = 0;
 
   int64_t offset_nanoseconds() const;
   void set_offset_nanoseconds(int64_t offset_nanoseconds);