Make dropdown filters consistent across the app

Problem to solve

Similar to https://gitlab.com/gitlab-org/gitlab-ee/issues/13148 - when we consider modifying the filter dropdowns, we should also make sure the dropdowns for similar filters are consistent across the app.

Example: filter options available (e.g. Any, None) and exactly what they filter.

Further details

We define "ANY" differently in different places in the product, which is confusing and could return unexpected results for user. For example, our search filter (any = not-null) vs the board scope (Any = not-null AND null).

Proposal

What does success look like, and how can we measure that?

The user can easily understand the difference between "any (not-null value)" and "any (not-null AND null)" value, and could be able to choose between the two. This experience should be consistent.