Create a legacy adaptor for PilotManager

PR #8233 has been a first attempt to to create a legacy adaptor for the `DIRAC/PilotManagerHandler -> DiracX/Pilots`. Nonetheless, there are few issues with it.

- it is mixing some PilotManagerHandler simplifications with the main objective
- some parts of what is in there needs https://github.com/DIRACGrid/diracx/pull/421, which is a superset of https://github.com/DIRACGrid/diracx/pull/570. This last one is the only one we want to merge right now
- it doesn't implement `getPilotOutput`, for which a solution should be found (maybe moved to another Handler)
- it doesn't implement `getPilotLoggingInfo`

Separate PRs will be done for solving each of the issues. The first one will only include PilotManagerHandler simplifications (effectively, removals).

Update:

- Can reuse #8696 : need to be tested with DiracX, make sure that everything is there

## DoD

- We can use the DiracX Pilot service through the legacy adaptor of DIRAC (to use it transparently from DIRAC)