Have you tried asking the question on a kubernetes forum?   It doesn’t look like a transformers problem to me.  (However, the huggingface people are smart cookies, so they might know anyway I suppose).
Are you hoping to get the system to release the 600mb after use, or do you want to keep the model loaded and persuade the system to use the same loaded model each time?
Have you considered using a smaller model?   You could maybe prune the distilBERT model you currently have.