Reland "[Site settings] Add feature in fieldtrial_testing_config.json"

This is a reland of commit cbcc5ca08b553f37d54715d3ecb17c7323368f18

Original change's description:
> [Site settings] Add feature in fieldtrial_testing_config.json
>
> This CL adds `PermissionSiteSettingsRadioButton` feature in
> fieldtrial_testing_config.json.
>
> Bug: 41494473
> Change-Id: Iccd12c907e0d8b0c49d420bcd0c04fdd220ca8d8
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6421902
> Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
> Commit-Queue: Yifan Luo <lyf@chromium.org>
> Reviewed-by: Elias Klim <elklm@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#1459626}

Bug: 41494473
Change-Id: I4414656820bf64e9f8e27fa6a158265393dd8e3f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6543969
Commit-Queue: Yifan Luo <lyf@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Elias Klim <elklm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1461313}