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

[ShGKme]

☑️ Resolves

• Ref: Library size report #7196
  • <NcTimezonePicker> is the 8th largest component
  • It also makes <NcDateTimePicker> large
• Most of the component size is the complete TZ database from @nextcloud/timezones
• With a wide Intl support, it can be replaced with Intl
• Result: component self-size (without NcSelect) drops from 200kb to 3kb (98.5% reduction)

🖼️ Screenshots

Component	Before	After
NcSelect	100.95 kb	100.95 kb
NcTimezonePicker	306.93 kb	103.00 kb (🔻 66.44%)
NcDateTimePicker	555.23 kb	350.58 kb (🔻 36.86%)
NcTimezonePicker - NcSelect	206.00 kb	2.05 kb (🔻 99.00%)
NcDateTimePicker - NcSelect	454.28 kb	249.63 kb (🔻 45.05%)

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 2️⃣ Backport to stable8 for maintained Vue 2 version or not applicable

[st3iny]

Tested and works.

[Antreesy]

Otherwise good

[ShGKme]

/backport to stable8

[backportbot]

The backport to stable8 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable8
git pull origin stable8

# Create the new backport branch
git checkout -b backport/7522/stable8

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 465fcfb6 958351a2

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/7522/stable8

Error: Failed to check for changes with origin/stable8: No changes found in backport branch

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Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.