changing about brave icon under "brave://settings" so it matches correct channel

[kjozwiak]

Description

We should change the Brave icon that's displayed at the bottom left corner next to About under brave://settings/ so it matches the correct channel.

Steps to Reproduce

1. open a nightly or a dev version of Brave
2. visit brave://settings/ and you'll notice that the Brave icon next to About is the official icon which is used for the release channel

Actual result:

Expected result:

Probably a good idea to use the correct channel icon rather than the official release icon

Reproduces how often:

100% reproducible using the above STR

Brave version (brave://version info)

Brave	0.70.9 Chromium: 76.0.3809.72 (Official Build) nightly (64-bit)
Revision	5a04c669126f657f98824b436555cae41b8f4146-refs/branch-heads/3809@{#897}
OS	Mac OS X

Brave	0.69.95 Chromium: 76.0.3809.62 (Official Build) dev (64-bit)
Revision	7b77856b3aa34d72f246d12340fc1ded8b2c0e83-refs/branch-heads/3809@{#798}
OS	Mac OS X

Version/Channel Information:

• Can you reproduce this issue with the current release? No
• Can you reproduce this issue with the beta channel? No
• Can you reproduce this issue with the dev channel? Yes
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

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

Miscellaneous Information:

[bsclifton]

This has been fixed at some point 😄