Sometimes Sync chain code modal is skipped after creating sync chain

[btlechowski]

Sync chain code modal is skipped after quickly clicking Computer during Choose Device Type

Important: Reproducible on 1.5.x, 1.4.x, 1.3.x. Not reproducible on 1.2.x

Steps to Reproduce

1. Clean profile
2. Open brave://sync/
3. Click Start a new sync chain
4. Immediately after Choose Device Type modal is shown, click Computer

Actual result:

Sync chain code modal is skipped.
Single device sync chain is created

Expected result:

Sync chain code modal is shown

Reproduces how often:

100% repro rate with above STR

Brave version (brave://version info)

Brave	1.3.106 Chromium: 79.0.3945.130 (Official Build) beta (64-bit)
Revision	e22de67c28798d98833a7137c0e22876237fc40a-refs/branch-heads/3945@{#1047}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

Brave	1.5.75 Chromium: 80.0.3987.66 (Official Build) nightly (64-bit)
Revision	56ea77d65c47ecbb1180b99f860d85b51117864a-refs/branch-heads/3987@{#662}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

Version/Channel Information:

• Can you reproduce this issue with the current release? no
• Can you reproduce this issue with the beta channel? yes
• Can you reproduce this issue with the dev channel? yes
• Can you reproduce this issue with the nightly channel? yes

cc @brave/legacy_qa @cezaraugusto @jsecretan @AlexeyBarabash @darkdh @rebron @bsclifton