Unexpected behaviour of `beforeEach` outside of suite without test isolation

What is the problem this feature will solve?

In test runners such as jest or vitest, callbacks passed to the methods before, after, beforeEach or afterEach not wrapped in any describe, are called only when tests in their module are about to start or end. That's also the current behaviour when --test-isolation=process. Unfortunately, when the --test-isolation is none, the callbacks we pass to those 4 functions are added as global callbacks and they start to be called before/after each test in any file.

That's unexpected behaviour and it makes it more difficult to migrate from other test runners to node test runner or from the default --test-isolation=process.

What is the feature you are proposing to solve the problem?

Each module should be wrapped in a suite by default, so the callbacks don't leak to the other test modules. The only exception should be callbacks that we pass to those 4 methods in the global setup file(or its imports I guess).

首先跟踪 Node.js 测试运行器在 --test-isolation=process 和 --test-isolation=none 下如何处理 before、after、beforeEach 和 afterEach 回调。检查不同测试模块之间现有的行为，包括全局设置及其导入。完成的标准是：模块级回调不再为其他模块中的测试运行，同时全局设置回调保留其预期作用域。