Update chromium strings to change 'incognito' to 'private'

[petemill]

This is the auto-generated output as a result from brave/brave-browser#1890
Any desired changes to this output will have to result in a change to the re-basing script, and a re-generation of these files.

Re-land #683
Fix brave/brave-browser#738

Note that this should probably only land on a release branch where the updated strings will be sent for translation updates. This is because language translations are hashed against the source English string, and therefore will be invalidated by these updates.

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Windows
  • macOS
  • Linux
• Verified that these changes pass automated tests (npm test brave_unit_tests && npm test brave_browser_tests) on
  • Windows
  • macOS
  • Linux
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone

Test Plan:

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

[bbondy]

We can't change generated grd and grdp files directly.

[petemill]

@bbondy this is just the generated output from brave/brave-browser#1890 which is still awaiting review

[bbondy]

Gotcha, why not the same PR?

[petemill]

@bbondy different repo

[bbondy]

Approved but pls regenerate the files again.

[kjozwiak]

Clearing the uplift-request/0.57.x-Beta flag. As per process, please re-submit for approval once this has landed in master and requires uplift into 0.57.x.

Could we get this merged into master ASAP and get another uplift approval as @bbondy is planning on ordering translations in the next few days.

[bbondy]

Uplifted since this is a strings update.
master: d76c724
0.58.x: 6dbeae2
0.57.x: 6d341e2