fix: use dynamic UTC expectations in date_proto_set_utc_hours test for timezone portability

[Deepak-negi11]

Fixes #4678

Problem

Some tests in builtins::date::tests were constructing dates using the
local-time Date constructor:

new Date(2020, 6, 8, 9, 16, 15, 779)

This interprets arguments as local time, so the resulting UTC components
vary depending on the timezone of the machine running the tests.

For example, in IST (UTC+5:30), local 9:16 becomes UTC 3:46 — the minutes
shift by 30. This caused date_proto_set_utc_hours to fail because the test
expected UTC minutes to be 16, but they were actually 46.

Fix

Replaced the local-time constructor with Date.UTC():

new Date(Date.UTC(2020, 6, 8, 9, 16, 15, 779))

Date.UTC() always interprets its arguments as UTC directly, so the UTC
components are consistent regardless of the machine's timezone.

Testing

• ✅ date_proto_set_month
• ✅ date_proto_set_utc_hours

Tested on IST (UTC+5:30) where the bug was originally discovered.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,862	52,862	0
Passed	49,497	49,497	0
Ignored	2,261	2,261	0
Failed	1,104	1,104	0
Panics	0	0	0
Conformance	93.63%	93.63%	0.00%

[jedel1043]

I don't think this is the correct fix; we cannot just leave local time resolution untested. A correct fix would fetch the current datetime externally (maybe with the time crate?), then check equality with the date returned by Date.

You pushed an unrelated commit btw 😅

[jedel1043]

But I guess we could also apply this and have a separate set of tests for local date + setUTC.

[Deepak-negi11]

@jedel1043 can you please review it again

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.94%. Comparing base (6ddc2b4) to head (c62bcbe).
⚠️ Report is 673 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4660      +/-   ##
==========================================
+ Coverage   47.24%   56.94%   +9.69%     
==========================================
  Files         476      549      +73     
  Lines       46892    60129   +13237     
==========================================
+ Hits        22154    34238   +12084     
- Misses      24738    25891    +1153     

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