In this PR (https://github.com/consul/consul/pull/4683) a new syntax was introduced
in the component specs to check that the component was not rendering.
It seems interesting to add this syntax to the rest of the cases and thus unify the way
we check that a component is not rendering.
We've had an accessibility error reported by the Spanish "Portal
Administración electrónica" (PAe). While I can't find any accessibility
rule saying empty lists should be avoided, it looks like some screen
readers report finding lists with 0 items, which is annoying.
We could also do it with CSS using `ul:empty { display: none}`. However,
at the time of writing no browser supports this rule when the tag
contains whitespace.
