Update all_elements to require constraints

What does this MR do?

This makes all_elements more reliable because it imposes certainty on when Capybara should stop looking for elements.

Closes https://gitlab.com/gitlab-org/quality/team-tasks/issues/86

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content