Disable desktop sharing hub on stable channel

[simonhong]

Resolves brave/brave-browser#20757

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:

[mkarolin]

Not sure we'd care to have OS_CHROMEOS here.

[mkarolin]

++

[kjozwiak]

Verification PASSED on Win 11 x64 using the following build:

Brave | 1.37.10 Chromium: 98.0.4758.74 (Official Build) nightly (64-bit)
-- | --
Revision | d0fe1ec4df090cd3eb02b591228505e12ea476e9-refs/branch-heads/4758@{#935}
OS | Windows 11 Version 21H2 (Build 22000.438)

• visited https://github.com and ensured that the Share this page icon was still visible/functional
• visited https://videocardz.com ensured that the Share this page icon was still visible/functional
• ensured that Copy Link, QR Code & Save page as... is working as expected
• ensured that the social media buttons are working as expected

Unfortunately I can't check to ensure that the share button is disabled on 1.35.x & and enabled on 1.36.x until #12055 & #12056 are uplifted we get new builds.