Fixing memory leak when GC is not called in datasmith mesh exporter
#jira UE-87989
#review-11255122 JeanMichel.Dignard
#rb JeanMichel.Dignard
[CL 11461470 by benoit deschenes in 4.25 branch]
#rnx
#rb none
#ROBOMERGE-SOURCE: CL 10869240 via CL 10869516 via CL 10869902
#ROBOMERGE-BOT: (v613-10869866)
[CL 10870584 by ryan durand in Main branch]