cubicweb-worker #4881269 [gc] stop destroying "old" tasks by default [validation pending]

It's up to the application to have a well defined policy wrt old tasks.
Let's provide the functionality, but not just activated by default.

prioritynormal
typeenhancement
done in3.2.0
load0.100
load left0.000
closed by#2521b3320c5e [hooks] by default, do not delete the old (in a terminal state) tasks
patch[hooks] by default, do not delete the old (in a terminal state) tasks [applied]