[stable5.0] fix: handle timezones with no transitions properly

[backportbot]

Backport of PR #6478

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 15.43%. Comparing base (27997b8) to head (e352ef0).
Report is 3 commits behind head on stable5.0.

Additional details and impacted files

@@            Coverage Diff             @@
##           stable5.0    #6487   +/-   ##
==========================================
  Coverage      15.43%   15.43%           
==========================================
  Files            206      206           
  Lines           9441     9441           
  Branches        2204     2204           
==========================================
  Hits            1457     1457           
  Misses          7665     7665           
  Partials         319      319           

Flag	Coverage Δ
javascript	15.43% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.