There is still a chance to get an RP-PVP realm, at least for the larger regions. Here is the thread that has been going on for quite some time now. Feel free to add your support: #RP-PVP Realms, Reconsider One Realm - #928 by Cybaster-cenarion-circle
On topic: Stress tests aren’t for playing the game per se. You want everyone on the same server if possible to push the limits of what that server can handle, so less is more in this case. Plus RP realms don’t have any technical differences to test, it’s just a different rule-set for player behavior attached to a PvE(normal) or PvP realm.