chore!: remove --env from llama stack run

[ehhuang]

What does this PR do?

user can simply set env vars in the beginning of the command.FOO=BAR llama stack run ...

Test Plan

Run
TELEMETRY_SINKS=coneol uv run --with llama-stack llama stack build --distro=starter --image-type=venv --run

---

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• chore!: remove --image-type and --image-name from llama stack run #3714
• -> chore!: remove --env from llama stack run #3711

[ashwinb]

I agree. I have no idea why I added these.

[leseb]

CONTRIBUTING.md:uv run --env-file .env -- pytest -v tests/integration/inference/test_text_inference.py --text-model=meta-llama/Llama-3.1-8B-Instruct
docs/docs/contributing/index.mdx:uv run --env-file .env -- pytest -v tests/integration/inference/test_text_inference.py --text-model=meta-llama/Llama-3.1-8B-Instruct
llama_stack/core/build.py:            "--env-name",
llama_stack/core/build_venv.sh:  echo "Usage: $0 --env-name <env_name> --normal-deps <pip_dependencies> [--external-provider-deps <external_provider_deps>] [--optional-deps <special_pip_deps>]"
llama_stack/core/build_venv.sh:  echo "Example: $0 --env-name mybuild --normal-deps 'numpy pandas scipy' --external-provider-deps 'foo' --optional-deps 'bar'"
llama_stack/core/build_venv.sh:    --env-name)
llama_stack/core/build_venv.sh:        echo "Error: --env-name requires a string value" >&2
llama_stack/core/build_venv.sh:  echo "Error: --env-name and --normal-deps are required." >&2
llama_stack/env.py:            f"\n3. Pass directly to pytest: pytest --env {key}=your-key"
tests/README.md:- Any API keys you need to use should be set in the environment, or can be passed in with the --env option.
tests/integration/README.md:- `--env`: set environment variables, e.g. --env KEY=value. this is a utility option to set environment variables required by various providers.
tests/integration/conftest.py:    env_vars = config.getoption("--env") or []
tests/integration/conftest.py:    parser.addoption("--env", action="append", help="Set environment variables, e.g. --env KEY=value")

missing a few