Hide rejected comments in threads too

[rohitpaulk]

We hide rejected comments under a button ("Show XX rejected comments") by default, so that staff can visualize what the comments page looks like to a regular user.

You can see this button at the bottom here:

Let's do this same treatment for comment threads - rejected comments in threads should be hidden under the button too, in the screenshot above the rejected ones are visible so it's hard for staff to visualize what the page looks like to a regular user