refactor da tests

[gupadhyaya]

following up on the comments from https://github.com/rollkit/rollkit/pull/1346

[follow up] waiting for n number of blocks to be produced is a pretty common thing. We should maybe think of how to refactor this into a helper method from go-da Originally posted by @MSevey in https://github.com/rollkit/rollkit/pull/1346#discussion_r1409697542

[non-blocking] this is set to 1 second in a few places. Should it be a constant? Originally posted by @MSevey in https://github.com/rollkit/rollkit/pull/1346#discussion_r1409699979

[follow up] we should maybe move this to tests/mocks since each package is defining it Originally posted by @MSevey in https://github.com/rollkit/rollkit/pull/1346#discussion_r1409701599

[follow up] same as the mock da helper, this could be moved to test/mocks Originally posted by @MSevey in https://github.com/rollkit/rollkit/pull/1346#discussion_r1409702107