Enable kExtensionsManifestV2 via Griffin (100% on Beta and Release)

[ShivanKaul]

Description

kExtensionsManifestV2 controls the Manifest V2 supported extensions page in brave://settings/extensions. We should enable it via Griffin.

Steps to reproduce

1. Go to brave://flags/#brave-extensions-manifest-v2

Actual result

It's off by default

Expected result

It should be on (via Griffin)

Reproduces how often

Easily reproduced

Brave version (brave://version info)

It's on in Nightly, we want to turn it on in Beta and Release

Channel information

• release (stable)
• beta
• nightly

Reproducibility

• with Brave Shields disabled
• with Brave Rewards disabled
• in the latest version of Chrome

Miscellaneous information

No response