Reduce LFS usage in CI

[davorrunje]

Why are these changes needed?

Related issue number

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• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/docs/contributor-guide/documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
autogen/oai/openai_utils.py	0.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (8541b30) and HEAD (f53ea40). Click for more details.

HEAD has 1169 uploads less than BASE

Flag	BASE (8541b30)	HEAD (f53ea40)
3.13	84	0
ubuntu-latest	120	1
commsagent-discord	9	0
optional-deps	132	0
3.10	94	0
3.9	73	0
browser-use	3	0
core-without-llm	14	1
macos-latest	105	0
windows-latest	116	0
3.11	51	1
commsagent-slack	9	0
3.12	39	0
commsagent-telegram	9	0
crawl4ai	9	0
docs	6	0
graph-rag-falkor-db	6	0
interop	9	0
interop-crewai	9	0
interop-langchain	9	0
interop-pydantic-ai	9	0
jupyter-executor	9	0
twilio	9	0
retrievechat-pgvector	10	0
retrievechat	15	0
retrievechat-mongodb	10	0
retrievechat-qdrant	14	0
agent-eval	1	0
gpt-assistant-agent	3	0
anthropic	15	0
lmm	3	0
teachable	3	0
gemini	14	0
cerebras	14	0
retrievechat-couchbase	3	0
groq	14	0
llama-index-agent	3	0
websurfer	15	0
mistral	14	0
bedrock	14	0
long-context	3	0
ollama	14	0
cohere	15	0
swarm	14	0
reasoning	14	0
together	14	0

Files with missing lines	Coverage Δ
autogen/_website/process_notebooks.py	41.56% <100.00%> (+0.30%)	⬆️
...hat/realtime/experimental/clients/gemini/client.py	48.59% <100.00%> (+1.48%)	⬆️
autogen/io/websockets.py	89.61% <ø> (ø)
autogen/oai/completion.py	17.99% <100.00%> (+0.11%)	⬆️
autogen/oai/openai_utils.py	64.63% <0.00%> (+0.52%)	⬆️

... and 43 files with indirect coverage changes