Support trial licenses inside enterprise_trial orchestration licenses

[pebrc]

Currently enterprise_trial orchestration licenses can only contain short-lived enterprise or platinum licenses (which one is applied depends on the version of Elasticsearch). This is confusing to users which expect a trial to be running if they apply a trial license. This PR prepares the ground to remedy this confusion by consistently using trial license across both the orchestrator and the Elastic stack.

I have adjusted the existing e2e test to cover both cases, which means we no longer test the "I can apply the same enterprise_trial multiple times (as long as it's valid)". But I would argue that this is only about being able to apply a regular enterprise license to Elasticsearch which we are already covering in another test. So instead we now testing once the old-style enterprise_trial with short-lived enterprise and platinum stack licenses and once the new-style enterprise_trial with a stack trial license inside.

[barkbay]

LGTM