only load the lifecycle, bus and event once to make test faster

[TestBoost]

The test class ClassUnwrapperTest tries to load the lifecycle, bus and event before every test runs in this test class.

For event, the test class ServletContextEvent creates it with a mocked class and it is only used when starting the application using lifecycle.

For lifecycle, it is only used to start an application with the event and called with getBeanManager().

For bus, it is only used to get certain properties of certain class name.

For all these three fields, the two tests inside the ClassUnwrapperTest are not trying to modify them but just accessing them. Repeatly creating lifecycle, bus and event object will increase the cost of running tests. When run on our own machine, the test runtime can jump from 5.4858 s to 4.5919 s after applying the changes.

[reta]

Thank you for contribution @TestBoost !