Fix a broken spec

What does this MR do?

It fixes a broken spec. I'm surprised this was only transient and not a consistent failure...

I guess what happened was that the first expect_mr_list_count(1) was happening before the filtering actually happened so there was still 1 MR in the list, and then the second expect_mr_list_count(1) sometimes was succeeding for the same reason (because the actual filtering is slow, but the tokens are updated instantly in the filter bar), and sometimes was failing, when the filtering happened before expect_mr_list_count(1)...

Closes #31443 (closed)