[stable8] perf(NcTimezonePicker): use Intl to reduce self-size from 206kb to 2kb

[ShGKme]

☑️ Resolves

• Manual backport: perf(NcTimezonePicker): use Intl to reduce self-size from 206kb to 2kb  #7522
• On top of: [stable8] refactor(NcTimezonePicker): migrate component to Typescript #8075

[codecov]

Codecov Report

❌ Patch coverage is 23.52941% with 26 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.94%. Comparing base (e2d4b2a) to head (dc19d90).
⚠️ Report is 2 commits behind head on stable8.

Files with missing lines	Patch %	Lines
...c/components/NcTimezonePicker/NcTimezonePicker.vue	27.58%	21 Missing ⚠️
src/components/NcTimezonePicker/timezoneUtils.ts	0.00%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           stable8    #8076      +/-   ##
===========================================
+ Coverage    45.54%   45.94%   +0.39%     
===========================================
  Files          193      192       -1     
  Lines         4797     4769      -28     
  Branches      1176     1168       -8     
===========================================
+ Hits          2185     2191       +6     
+ Misses        2519     2492      -27     
+ Partials        93       86       -7     

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