Fix dependency problem with functor cache and GaudiConfig2

@clemenci is this relevant also for master or also in legacy branches?

... I would say only run2

added backport run2 label

/ci-test --merge

• [2020-04-24 09:37] Validation started with lhcb-master-mr#717

resolved all threads

unassigned @dovombru

approved this merge request

unassigned @rmatev

merged

mentioned in commit 7665e55a

added Build enhancement labels

mentioned in commit 55941130

mentioned in merge request !2545 (merged)

cherry-picked into !2545 (merged)

removed backport run2 label

mentioned in issue Moore#163 (closed)

mentioned in commit f9eedd9f

mentioned in merge request !2670 (merged)

mentioned in commit e161678c