Fixed wrong region list name mapping

[simonhong]

f/u PR for #25596
fix brave/brave-browser#41227

it should be "eu-en".

Resolves

Submitter Checklist:

• I confirm that no security/privacy review is needed and no other type of reviews are needed, or that I have requested them
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Squashed any review feedback or "fixup" commits before merge, so that history is a record of what happened in the repo, not your PR
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally:
  • npm run test -- brave_browser_tests, npm run test -- brave_unit_tests wiki
  • npm run presubmit wiki, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on
• All relevant documentation has been updated, for instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Web-Compatibility-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

1. Live in england(london) to get current timezone as eu-en
2. Launch with clean profile
3. Setup VPN as purchased
4. No crash!

[deeppandya]

LGTM

[MadhaviSeelam]

Verification PASSED using

Brave | 1.72.37 Chromium: 129.0.6668.59 (Official Build) nightly (64-bit)
-- | --
Revision | c0271c2db30a45dc80f44487ee2e84212cfef92e
OS | Windows 11 Version 23H2 (Build 22631.4169)

Pre-requisite: Changed the region/time zone to London in Windows settings

1. Installed 1.72.37
2. launched Brave
3. logged into account.bravesoftware.com with existing VPN subscription credentials
4. clicked Refresh Firewall + VPN button
5. verified Brave VPN credentials are now loaded on this device message is shown
6. clicked VPN button
7. toggled on/off to enable VPN in the VPN panel
8. opened whatismyipaddress.com in a new tab

• Confirmed no crash occurred.
• Confirmed VPN server is auto-selected to England
• Confirmed successfully enabled/disabled VPN
• Confirmed correct region is shown in whatismyipaddress.com page

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