Fix ZK Rollup test (Follow-up from "Proto/Tests: fix ignored values (part 2/3)")

The following discussion from !6579 (merged) should be addressed:

• @mbouaziz started a discussion: (+1 comment)

  @paracetamolo @alocascio

  CI fails with this change: https://gitlab.com/tezos/tezos/-/jobs/3200831107

  Did you really intent to ignore the error? If so, it should be made explicit with a type annotation. If not then you should fix the test