Improve on the Rewards opt-in screen surfacing behavior

[ghost]

Description

Current behavior is to only surface the Rewards opt-in overlay once to avoid race issues around enabling ads.
Perhaps we can improve upon this behavior in the future to better the UX.

Steps to reproduce

1. Click on the BAT panel after launching the browser
2. Close the panel and navigate to the settings page
3. You will see that you can easily bypass the opt-in screens through this route.

Version/Channel Information:

• Can you reproduce this issue with the current Play Store version?
• Can you reproduce this issue with the current Play Store Beta version?
• Can you reproduce this issue with the current Play Store Nightly version?

Device details

• Install type (ARM, x86): ARM
• Device type (Phone, Tablet, Phablet): Phone
• Android version: 9

Brave version

1.20.23