Keeping Request-OTR visits out of Rewards' AC list

[fmarier]

The Request-OTR feature allows websites to opt-in to having their visits not show up locally on the device (as if the site had been visited in a private window). These requests therefore should not show up in the list of publishers that will be rewarded as part of auto-contribute for users opted into Rewards.

(I've not tested this to see whether or not it's handled properly, so testing would be the first step.)

[Miyayes]

Intersection between Verified sites and sites that have OTR is likely small. However, we should still do this.