Make featured data stories images rectangular on the topic page

[roll]

First options is:

to reduce images amount from 4 to 3 because there are less space than on the homepage.

---

Another option is to reduce its height:

.topic.details {
  & img {
    height: 150px;
  }
}

instead of this PR changes

[roll]

Rebased on height reducing to preserve 4 images