Modify Behat tests to ensure tests still pass.

During the development of the new navigation bar it is possible that existing behat tests may start failing.
Before we consider the navigation bar work done, we need to ensure we are not introducing new failures by migrating existing behat tests to the new navigation where required.

It could be possible that we need to deprecate existing behat steps or migrate them over to theme_classic's behat step overrides and implement new steps for theme_boost/Moodle core

Acceptance criteria

• Existing behat tests continue to pass across both classic & boost (no introduced failures)