[JENKINS-35198] - DelegatingComputerLauncher should accept child classes in its hooks (#2384)

* JENKINS-35198 Add failing test for clear identification of the issue and future regression test

* JENKINS-35198 Fix DelegatingComputerLauncher logic for filtering out subclasses as possible delegates

this logic is by default, and subclasses can still allow the selection of other DelegatingComputerLauncher instances as delegates.