Set explicit limit for getPosts/getComments in tests

[Nutomic]

Looking at CI test failures, I noticed there were a couple cases where the expected value wasnt found in return value from getPosts():

  ● moderator view

    expect(received).toContain(expected) // indexOf

    Expected value: 35
    Received array: [34, 27, 26, 22, 21, 20, 19, 15, 14, 13]

      295 |   let commentIds = comments.map(comment => comment.comment.id);
      296 |
    > 297 |   expect(postIds).toContain(otherPost.post.id);
          |                   ^
      298 |   expect(commentIds).toContain(otherComment.comment.id);
      299 |
      300 |   expect(postIds).toContain(alphaPost.post.id);

      at Object.<anonymous> (src/community.spec.ts:297:19)

https://woodpecker.join-lemmy.org/repos/129/pipeline/4262/20
https://woodpecker.join-lemmy.org/repos/129/pipeline/4276/20

This seems to happen because it uses the default limit which is 10, but there are more posts than that and the expected value is not returned. So setting an explicit, high limit should resolve this.