Fixes leaking of full version via navigator.userAgentData.getHighEntropyValues

[mkarolin]

Fixes brave/brave-browser#23491

It seems uaFullVersion was always leaking but the fullVersionList started leaking because of the change in
#14155 where brand was added to GetUserAgentBrandList function in
components/embedder_support/user_agent_utils.cc which broke the BraveContentBrowserClient::GetUserAgentMetadata expectation that the brand list would only contain 2 items (instead of now 3).

This fix adjusts the BraveContentBrowserClient::GetUserAgentMetadata expectations and removes adding the Brave brand to the lists because it's already there. Now we just zero out the 3 last components of the full versions list and uaFullVersion string.

Also, adds a browser test to check the sizes of the lists and versions values.

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, npm run lint, 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:

[ShivanKaul]

LGTM! Thanks for adding the tests too

[kjozwiak]

Verification PASSED on Win 11 x64 using the following build(s):

Brave | 1.48.34 Chromium: 108.0.5359.94 (Official Build) nightly (64-bit)
-- | --
Revision | 713576b895246504ccc6b92c2fb8ce2d60194074-refs/branch-heads/5359_71@{#3}
OS | Windows 11 Version 22H2 (Build 22621.819)

Using the information provided via brave/brave-browser#23491 (comment), went through the following and ensured that we're not leaking the full version via fullVersionList as per the following:

1.48.22 Chromium: 108.0.5359.71	1.48.34 Chromium: 108.0.5359.94