Sync clear orders map

[AlexeyBarabash]

Fixes brave/brave-browser#2367 .

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:

1. Create sync chain on device 1
2. Join device 2 and add a bookmark on device 2, gets sync'd to device 1
3. Import 5000 bookmark HTML file on device 1, wait for a really long time to sync bookmarks into device 2
4. Expand the very nested folder in bookmarks on device 2, see some bookmarks at a wrong position compare to device 1

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

[darkdh]

s/OrdersMap/OrderMap/g

[AlexeyBarabash]

Done force push of change OrdersMap => OrderMap according to the review.

[darkdh]

++

[AlexeyBarabash]

master: a11bb37
0.60.x: daa3fa0

[AlexeyBarabash]

0.59.x: 085f376

[rebron]

After deliberating with @kjozwiak, keep this pr in 59.x and uplift-approved. @darkdh don't set the uplift-approved flags, just uplift-requests. We'll get to them quickly. We need to see and control what's getting in during the freeze period.

[darkdh]

sorry, I was putting the wrong label. I meant to put uplift-request