[ATR-25805] Downgrade WARNING to DEBUG in TrigNavSlimmingMTAlg
Downgrade WARNING to DEBUG in conversion of trigger features to four-vectors in the DAOD due to not having a TriggerAPI to prevent inappropriate chains features being attempted to be converted.
Would suggest to re-instate this after the TriggerAPI is reincluded, it could then help to find misconfigured chains, or misconfigurations in the TriggerAPI, or highlight the need for additional bespoke handling in derivations of non-IParticle conformant trigger physics objects.