[PWGJE] fix of broken bc retrieval in derivedDataProducer

[fjonasALICE]

fixed critical runtime error in processCollisions function of derivedDataProducer:

[ERROR] SEVERE: Device jet-deriveddata-producer (3863890) had at least one message above severity 7: Unhandled o2::framework::runtime_error reached the top of main of o2-analysis-je-jet-deriveddata-producer, device shutting down. Reason: Trying to dereference index with a wrong type in bc_as<T> for base target "BCs". Note that if you have several compatible index targets in your process() signature, the last one will be the one actually bound.

resolved with this PR

[github-actions]

O2 linter results: ❌ 10 errors, ⚠️ 33 warnings, 🔕 0 disabled