Remove Gemma 3-4B multimodal redundant variable and optimize vllm_decode hbm_utilization of Lama3.1-70b to prevent OOM

[chiajunglien]

Description

This PR removes the redundant variable in tests/end_to_end/tpu/gemma3/4b/test_gemma3_multimodal_sft.sh and adjust the hbm_utilization_vllm of vllm_decode in tests/end_to_end/tpu/llama3.1/70b/test_llama3.1_70b_rl.sh and tests/end_to_end/tpu/llama3.1/70b/test_llama3.1_70b_sft.sh

Tests

xpk workload create-pathways \
  --cluster=v5p-128-bodaborg-europe-west4-b \
  --workload=llama-povllm-$(date +%m%d%H%M) \
  --tpu-type=v5p-128 \
  --num-slices=1 \
  --priority=very-high \
  --project=cloud-tpu-multipod-dev \
  --zone=europe-west4-b \
  --skip-validation \
  --docker-image=[gcr.io/tpu-prod-env-multipod/maxtext_post_training_nightly:30411448246](http://gcr.io/tpu-prod-env-multipod/maxtext_post_training_nightly:30411448246) \
  --command="set -xue; \
    export TPU_MIN_LOG_LEVEL=0; \
    export TF_CPP_MIN_LOG_LEVEL=0; \
    export TPU_STDERR_LOG_LEVEL=0; \
    export JAX_PLATFORMS='proxy,cpu'; \
    export JAX_BACKEND_TARGET='grpc://127.0.0.1:29000'; \
    export ENABLE_PATHWAYS_PERSISTENCE='1'; \
    python3 -m maxtext.inference.vllm_decode \
      model_name=llama3.1-70b \
      tokenizer_path='meta-llama/Llama-3.1-70B-Instruct' \
      load_parameters_path='gs://cloud-tpu-multipod-dev-emma-data/llama3.1-70b-0729/rl/rl_test_0630/checkpoints/actor/5/model_params' \
      vllm_hf_overrides='{\"architectures\": [\"MaxTextForCausalLM\"]}' \
      hbm_utilization_vllm=0.6 \
      prompt='Suggest some famous landmarks in London.' \
      scan_layers=True \
      enable_single_controller=true \
      ici_tensor_parallelism=8"

Checklist

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• I have performed a self-review of my code. For an optional AI review, add the gemini-review label.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run end-to-end tests tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[gemini-code-assist]

Caution

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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