Address flakiness in Activity Log tests

[balanza]

I experienced some flakiness in some of our activity log tests we've recently introduced.

It seems there is some inconsistency in how we slice data in pages. For example here the test fails because it was expecting two identical lists of entries in next_logs_alt and next_logs, but they where different. By re-running the job, the error disappeared.

The problem may be in how we sort entries by date. As per the Elixir docs:

[...] avoid using the default sorting function to sort
structs, as by default it performs structural comparison instead of
a semantic one. In such cases, you shall pass a sorting function as
third element or any module that implements a compare/2 function.
For example, to sort users by their birthday in both ascending and
descending order respectively:

 iex> users = [
 ...>   %{name: "Ellis", birthday: ~D[1943-05-11]},
 ...>   %{name: "Lovelace", birthday: ~D[1815-12-10]},
 ...>   %{name: "Turing", birthday: ~D[1912-06-23]}
 ...> ]
 iex> Enum.sort_by(users, &(&1.birthday), Date)

The fix improves how we sort data. We should keep an eye on the overall test, to see if it's enough do remove the flakiness.