[Desktop] Sync v2 initial bookmarks duplication

[darkdh]

Description

The first device has to wait one sync interval(60s) to send its local bookmarks. When second device tries to do first time merge, it gets nothing from server.

Note: Chrome can reproduce this within 10s

Steps to Reproduce

1. bookmark brave://sync-internals/ on device A
2. bookmark brave://sync-internals/ on device B
3. Create sync chain on device A
4. Device B join sync chain shortly (less than 60s)

Actual result:

We will see both devices have same duplicate bookmarks

Expected result:

No duplicate bookmarks

Reproduces how often:

Always

Brave version (brave://version info)

Version/Channel Information:

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

However, this steps below won't have bookmark duplicated

1. bookmark brave://sync-internals/ on device A
2. bookmark  brave://sync-internals/ on device B
3. Create sync chain on device A
4. device B join sync chain after 60s or add a bookmark within 60s
5. There is no duplicate bookmarks

Miscellaneous Information:

[btlechowski]

Thanks @darkdh !

cc @brave/legacy_qa @rebron

[btlechowski]

QA/Blocked as it needs build higher than 1.12.111

[LaurenWags]

Removing QA/Blocked since https://github.com/brave/brave-browser/releases/tag/v1.12.112 is available

[btlechowski]

Verification passed on

Brave	1.12.112 Chromium: 84.0.4147.125 (Official Build) (64-bit)
Revision	d0784639447f2e10d32ebaf9861092b20cfde286-refs/branch-heads/4147@{#1059}
OS	Ubuntu 18.04 LTS

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

Verified test plan from the description

Verified test plan from #11104 (comment)

---

Verification passed on

Brave | 1.12.112 Chromium: 84.0.4147.125 (Official Build) (64-bit)
-- | --
Revision | d0784639447f2e10d32ebaf9861092b20cfde286-refs/branch-heads/4147@{#1059}
OS | Windows 10 OS Version 1903 (Build 18362.959)

Note: I was able to reproducible the issue once out of 5 attempts.

• Verified test plan from the description
  
• Encountered [Desktop] Devices are not synced after upgrade from V1 #11206

---

Verification PASSED on macOS 10.15.6 x64 using the following build:

Brave | 1.12.112 Chromium: 84.0.4147.125 (Official Build) (64-bit)
-- | --
Revision | d0784639447f2e10d32ebaf9861092b20cfde286-refs/branch-heads/4147@{#1059}
OS | macOS Version 10.15.6 (Build 19G73)

Verified the STR/Cases outlined via #11116 (comment) as per the following:

macOS Example	Windows Example

Also verified the STR/Cases outlined via #11104 (comment).

[kjozwiak]

@btlechowski should we create a follow up issue which will address this so it doesn't happen anymore. We should be good for the 1.12.x release as it's a major improvement but sounds like it's still occurring?

[btlechowski]

@kjozwiak Logged #11358 as follow up.