Issue: docling-serve GPU Memory Leak

### Question: docling-serve GPU Memory Leak

Description: docling-serve exhibits steadily increasing GPU memory usage over time when processing a consistent stream of documents, suggesting a memory leak. This leads to potential OOM errors.

Expected: GPU memory should plateau after model loading and remain relatively stable.

Actual: GPU memory usage continuously increases, as seen via nvidia-smi.

Steps to Reproduce:

Set up docling-serve with GPU backend (e.g., pdf_backend: dlparse_v2) and OCR enabled (do_ocr: true).
Send repeated requests to /v1alpha/convert/source or /v1alpha/convert/file with PDF documents. Example curl commands are provided in the original, longer issue description.
Monitor GPU memory usage with nvidia-smi.

How to avoid this for GPU limited resource environments?
I got an h100 with mig of 12GB VRAM but after 4 pdf is starts to throw OOM

docling serve request params
I use docling-serve with this params
params = {
"from_formats": [
"docx",
"pptx",
"html",
"image",
"pdf",
"asciidoc",
"md",
"csv",
"xlsx",
"xml_uspto",
"xml_jats",
"json_docling",
],
"to_formats": ["md"],
"image_export_mode": "placeholder",
"do_ocr": True,
"force_ocr": False,
"ocr_engine": "easyocr",
"ocr_lang": None,
"pdf_backend": "dlparse_v2",
"table_mode": "accurate",
"abort_on_error": False,
"return_as_file": False,
"do_table_structure": True,
"include_images": True,
"images_scale": 2.0,
}