Added don't show again button to obsolete system infobar

[simonhong]

fix brave/brave-browser#27122

W/o this, user will see this infobar whenever brave is launched.

Resolves

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:

1. Launch Brave on Win7/8 and check obsolete system infobar with don't show again button is shown
2. Click don't show again button and check infobar is hidden
3. Relaunch and check this infobar is not shown anymore

[simonhong]

Set as draft because kSuppressUnsupportedOSWarning prefs should be cleared when user did os update.

[simonhong]

It's ready to review. PTAL :)

[sangwoo108]

LGTM. But I'm not quite sure if it's good to suppress this warning. I feel like users could be exposed to potential danger by using an obsolete version - some security patches could be missing for these systems, I guess. So, I would prefer showing the warning even if it bothers them so that they could feel like updating the system. But it's just my persnoal preference.

[github-actions]

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[kjozwiak]

LGTM. But I'm not quite sure if it's good to suppress this warning. I feel like users could be exposed to potential danger by using an obsolete version - some security patches could be missing for these systems, I guess. So, I would prefer showing the warning even if it bothers them so that they could feel like updating the system. But it's just my persnoal preference.

Just adding some more context, users would also be able to see a warning regarding their Brave installs not getting updates via brave://settings/help as well whenever they go into Settings -> About Brave. Granted, not sure how many users would actually go there.