[Logs / Metrics UI] [NP followup] Add functional tests back

[Kerry350]

As part of #54583 some functional tests were removed. This was due to inconsistent behaviour of timezones within the functional tests when using a custom space (the default space will use utc, whilst custom spaces uses browser time). This led to issues with rendering actual data (which relies on a point in time).

The tests for asserting that the app is accessible just had their behaviour changed (we can ascertain the app is accessible without rendering data). However, the tests for the context menu are still removed.

We should re-add these in some context, but outside the realm of a custom space. Or we could keep the custom space, but we'd need to add some test code to navigate to the settings page, and change the timezone to utc first.

[elasticmachine]

Pinging @elastic/logs-metrics-ui (Team:logs-metrics-ui)