[TASK] Remove classFile option from services

When using services (sv), one had to add "classFile" to the info
array when registering a service in order to find the entered
className. As this is now completely taken care of by the autoloader,
the option is obsolete and is now deprecated.

Note that once this is in, the documentation needs to be adjusted
as well.

Change-Id: Ic8817c80f7646e071ba71fa498972b70115715c5
Releases: 6.1
Resolves: #37115
Reviewed-on: https://review.typo3.org/11150
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn