Force to refresh sync cycle(poll/nudge) when transiting from CONFIGURATION to NORMAL mode.

[darkdh]

This is to mitigate the chance of bookmarks duplication when first time
sync which is caused by first device send it local bookmarks only after
a poll interval(60s). When second device wants to do
BookmarkModelMerger::Merge(), it can't get anything from server because
first device hasn't sent any. So it commit its own bookmarks which will
cause duplication.

Note: Chrome has FCM invalidation ready so its first device will receive
notification within ~10s

Resolves brave/brave-browser#11116

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
  • Android
  • iOS
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• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
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• Verified that all lint errors/warnings are resolved (npm run lint)
• 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
• Public documentation has been updated as necessary. 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-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

STR in brave/brave-browser#11116

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

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.

[yrliou]

LGTM

[darkdh]

follow-up issue created brave/brave-browser#11118

[darkdh]

unrelated CI failure

4:32:01  [  FAILED  ] GreaselionServiceTest.ScriptInjectionWithPrecondition, where TypeParam =  and GetParam() =  (1358 ms)
14:32:01  [604/604] GreaselionServiceTest.ScriptInjectionWithPrecondition (1597 ms)
14:32:01  1 test failed:
14:32:01      GreaselionServiceTest.ScriptInjectionWithPrecondition (../../brave/browser/greaselion/greaselion_browsertest.cc:265)

https://ci.brave.com/job/pr-brave-browser-sync-v2-initial-merge/4/execution/node/648/log/

[btlechowski]

LGTM to uplift

Brave	1.14.25 Chromium: 84.0.4147.111 (Official Build) nightly (64-bit)
Revision	6efb4d9a67167fa201878f23b57e131cc5189e2d-refs/branch-heads/4147@{#967}
OS	Linux

I am still able to reproduce if I create the sync chain within few(2) seconds, but it is still a big improvement.