Return trials to frontend only when they are used

In the backend, an Experiment is stored together with its generated trials in memory, after an Experiment was created in the frontend.

For the Experiments list view we don't need the trials but they are still returned.

For many Experiments with large number of trials this leads to unnecessary transfer of information, slowing down the application, especially when the instance has limited resources.

We should only return (and even generate) the trials if a user opens the Experiment detail view.

追踪 Experiments 如何为 frontend 列表视图存储和返回，然后将该流程与 Experiment 详情视图进行比较。确认 trials 在哪里生成和传输；完成标准是列表响应避免未使用的 trials，而打开 Experiment 仍会生成并返回 trials。