Import fix for E2E tests

[SurbhiJainUSC]

Description

• Fix import for llama_or_mistral_ckpt
• Fix base output directory for Gemma2 and Gemma3 E2E tests

FIXES: b/447464486

Tests

python3 src/MaxText/utils/ckpt_scripts/llama_mistral_mixtral_orbax_to_hf.py src/MaxText/configs/base.yml base_output_directory=$OUTPUT_PATH load_parameters_path=$MODEL_CKPT_PATH run_name=llama_ckpt model_name=llama2-7b hardware=tpu hf_model_path=/tmp/llama2-7b

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[RissyRan]

Thanks for the fix! Let's consolidate path into #2635?