VPN onboarding modal flashes before loading the VPN modal state

[srirambv]

Description

VPN onboarding modal flashes before loading the VPN modal state

Steps to Reproduce

1. Enable VPN and connect to a node
2. Click on VPN button in URL bar
3. Before the modal loads VPN connect state it briefly flashes the onboarding screen

Actual result:

VPN.Onboard.screen.mov

Expected result:

Do not show onboarding screen before loading the actual modal state

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.41.17 Chromium: 102.0.5005.61 (Official Build) nightly (64-bit)
Revision	0e59bcc00cc4985ce39ad31c150065f159d95ad3-refs/branch-heads/5005@{#819}
OS	macOS Version 12.4 (Build 21F79)

Version/Channel Information:

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

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

Also seen this on #21754 & #22882

cc: @bsclifton @spylogsster @simonhong @brave/legacy_qa

[GeetaSarvadnya]

Could be macOS specific issue, not reproducible in Windows 10 x64

[MadhaviSeelam]

Verification PASSED using

Brave | 1.42.2 Chromium: 103.0.5060.53 (Official Build) nightly (64-bit)
-- | --
Revision | a1711811edd74ff1cf2150f36ffa3b0dae40b17f-refs/branch-heads/5060@{#853}
OS | Windows 11 Version 21H2 (Build 22000.739)

Reproduced in 1.41.47 Chromium: 102.0.5005.78 nightly using the recording. Faint onboarding modal flashed.

Confirmed the fix and onboarding modal no longer flashed.

[stephendonner]

Verified PASSED using

Brave	1.42.13 Chromium: 103.0.5060.53 (Official Build) nightly (x86_64)
Revision	a1711811edd74ff1cf2150f36ffa3b0dae40b17f-refs/branch-heads/5060@{#853}
OS	macOS Version 12.5 (Build 21G5046c)

Have reproduced the issue for a long time (thanks for filing, @srirambv !), and confirm I no longer can (it was definitely noticeable to the human eye, even as just a "flash"):