Disable copy-clean-link-by-default for osx

[spylogsster]

Resolves brave/brave-browser#29303

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:

• Check brave-copy-clean-link-by-default feature disabled by default for osx and enabled for other platforms

[LaurenWags]

Verified with

Brave | 1.51.64 Chromium: 112.0.5615.39 (Official Build) nightly (x86_64)
-- | --
Revision | a0e7b9718a92bcd1cf33b7c95316caff3fc20714-refs/branch-heads/5615@{#753}
OS | macOS Version 12.6.3 (Build 21G419)

macOS - PASSED

Confirmed with prior version (1.51.51 via #17673 (comment)), that default for brave://flags/#brave-copy-clean-link-by-default was enabled.

Using 1.51.64, confirmed default for brave://flags/#brave-copy-clean-link-by-default was disabled:

Case A: Ran through appropriate cases on https://fmarier.github.io/brave-testing/copy-clean-link.html to confirm functionality still works with the keyboard shortcut disabled. (spot check of "Copy clean link" functionality)

Case B: Ran through the below steps to confirm expected locations of "Copy clean link" option and confirm that keyboard shortcut (Cmd + C on macOS) is not used for "Copy clean link":

0. Confirmed value of "Default" for brave://flags/#brave-copy-clean-link-by-default
1. Visited https://dev-pages.bravesoftware.com/clean-urls/?brave_testing1=foo&brave_testing2=bar&brave_testing3=keep&&;b&d&utm_content=removethis&e=&f=g&=end
2. Clicked the URL bar and confirmed "Copy clean link" available from macOS app menu and it does NOT have the cmd + C keyboard shortcut (⌘C) listed next to it, this is listed next to "Copy" as expected
3. Right-clicked the URL and confirmed "Copy clean link" is in the context menu
4. Confirmed "Copy clean link" is displayed in the share menu from URL bar
5. Used "Cmd + C" while the URL bar is in focus to copy the URL
6. Opened a new tab and pasted the copied URL
7. Confirmed link pasted is the original URL with all parameters: https://dev-pages.bravesoftware.com/clean-urls/?brave_testing1=foo&brave_testing2=bar&brave_testing3=keep&&;b&d&utm_content=removethis&e=&f=g&=end
8. Opened a new tab and visited https://twitter.com/LBC/status/1577628501364146176?s=20&t=fpVMBMSfgI_pNGQxxpV6bw
9. Used "Cmd + C" while the URL bar is in focus to copy the URL
10. Opened a new tab and pasted the copied link
11. Confirmed link pasted is the original URL with all parameters https://twitter.com/LBC/status/1577628501364146176?s=20&t=fpVMBMSfgI_pNGQxxpV6bw

Step 0	Step 2	Step 3	Step 4	Step 7	Step 8	Step 11

---

Brave	1.51.64 Chromium: 112.0.5615.39 (Official Build) nightly (64-bit) 
Revision	a0e7b9718a92bcd1cf33b7c95316caff3fc20714-refs/branch-heads/5615@{#753}
OS	Windows 10 Version 21H2 (Build 19044.2486)

Windows - PASSED

Spot checked that the default for brave://flags/#brave-copy-clean-link-by-default was enabled.
Confirmed ctrl+C keyboard shortcut (as listed on context menu) copied the clean link.
Note - per comment on issue, this should be fully tested on 1.49.x. Can use "Default" (Enabled) case from brave/brave-browser#29177 (comment) as example on what to verify.

Example	Example	Example

---

Brave	1.51.64 Chromium: 112.0.5615.39 (Official Build) nightly (64-bit) 
Revision	a0e7b9718a92bcd1cf33b7c95316caff3fc20714-refs/branch-heads/5615@{#753}
OS	Linux

Linux - PASSED

Spot checked that the default for brave://flags/#brave-copy-clean-link-by-default was enabled.
Confirmed ctrl+C copied the clean link (as listed on context menu).Confirmed ctrl+C keyboard shortcut (as listed on context menu) copied the clean link.
Note - per comment on issue, this should be fully tested on 1.49.x. Can use "Default" (Enabled) case from brave/brave-browser#29177 (comment) as an example on what to verify.

Example	Example	Example