Hide iOS QR Code function in Rewards Settings

[bsclifton]

Description

The QR Code shown in Rewards settings will be used on iOS. While we finalize the solution for this (currently testing), we're going to hide the QR Code until it's 100% ready and all scenarios are tested.

For more information see:
brave/brave-ios#3115

[btlechowski]

QA/Blocked till we get a new build (> 1.18.69)

[btlechowski]

Verification passed on

Brave	1.18.70 Chromium: 87.0.4280.101 (Official Build) (64-bit)
Revision	9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS	Windows 7 Service Pack 1 (Build 7601.24544)

Verified QR code is not shown in Rewards Settings

---

Verification passed on

Brave	1.18.70 Chromium: 87.0.4280.101 (Official Build) (64-bit)
Revision	9407c80213cda69c2b7abcb4fa8e3f74488f4956-refs/branch-heads/4280@{#1807}
OS	Ubuntu 18.04 LTS

Verified QR code is not shown in Rewards Settings

[dodieboy]

@bsclifton Brave ios have released the rewards qr code feature on the official ios release already. Will this commit be revert?

[bsclifton]

@dodieboy the complication we had run into has been resolved in our staging environment. We're working towards a new desktop release and should have a fix in Nightly tomorrow (Friday). We'll then propagate to Beta and issue a hotfix for the stable version 😄

Thanks for your patience!

[bsclifton]

@dodieboy pull request created to re-show the QR code here 😄👍
brave/brave-core#7413