This change remove the support for Mockito annotations, `MockitoSession`
and opening/closing of mocks that was inherited from Boot's `@MockBean`
support, as well as the switch to `MockitoSession` made in 1c893e6.
Attempting to take responsability for things Mockito's own JUnit
Jupiter extension does better is not ideal, and we found it leads to
several corner cases which make `SpringExtension` and `MockitoExtension`
incompatible in the current approach.
Instead, this change refocuses our Mockito bean overriding support
exclusively on aspects specific to the Framework. `MockitoExtension`
will thus be usable in conjunction with `SpringExtension` if one needs
to use `@Captor`/`@InitMocks`/`@Mock`/`@Spy` or other Mockito utilities.
See gh-33318
Closes gh-33692