Remove hyphen from vpn os entry name

[simonhong]

Resolves brave/brave-browser#30295

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• 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 lint, 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/Custom-Headers
  • 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:

See steps from brave/brave-browser#30295

[bsclifton]

Nice find! Confirmed locally (after deleting ALL entries) that it works with this patch and fails WITHOUT this patch

Original issue should have only affected Beta/Nightly (and local builds if people did them, which uses Development profile)

[stephendonner]

Verification PASSED using

Brave	1.53.44 Chromium: 114.0.5735.26 (Official Build) nightly (64-bit)
Revision	7075cbb66f0542ac3e01ddfde6b813e7d61118a5-refs/branch-heads/5735@{#454}
OS	Windows 10 Version 22H2 (Build 19045.2965)

Steps:

1. installed 1.53.44
2. launched Brave
3. purchased, configured, and tried to connect to Brave VPN
4. however, it fails to write out the config (due to Follow up to #29512 - Brave VPN Connect failed with Failed to write the VPN config brave-browser#30291)
5. shut down Brave nightly
6. launched Brave release
7. purchased, configured, and connected to Brave VPN
8. confirmed a BraveVPN entry was written to Windows' VPN settings page
9. disconnected from Brave VPN
10. relaunched 1.53.44 nightly
11. connected to Brave VPN

Confirmed I could connect (once release wrote out the initial file), and the entry was named BraveVPNNightly

Step 4	Step 7	Step 8	Step 11	VPN panel