docs(build): clarify UBI9 compiler requirement and remove redundant test

- Added a comment in build_container.sh to explain why we install python3.11‑devel, gcc, and make on UBI9.
- Removed tests/integration/test_ubi9_toolchain.py and pytest.ini, as the test provided little value

tests/integration/test_ubi9_toolchain.py

@@ -1,29 +0,0 @@
-# Copyright (c) Meta Platforms, Inc. and affiliates.
-# All rights reserved.
-#
-# This source code is licensed under the terms described in the LICENSE file in
-# the root directory of this source tree.
-
-# tests/integration/test_ubi9_toolchain.py
-
-from pathlib import Path
-
-
-def test_ubi9_compiler_packages_present():
-    """
-    Verify that the UBI9 dnf install line in build_container.sh includes
-    python3.11‑setuptools, python3.11‑devel, gcc, and make.
-    """
-    script = (
-        Path(__file__).parents[2]  # moves from tests/integration up to repo root
-        / "llama_stack"
-        / "distribution"
-        / "build_container.sh"
-    )
-    content = script.read_text(encoding="utf-8")
-
-    expected = "python3.11-setuptools python3.11-devel gcc make"
-    assert expected in content, (
-        f"Expected to find '{expected}' in the UBI9 install line, but it was missing.\n\n"
-        f"Content of {script}:\n{content}"
-    )

tests/pytest.ini

@@ -1,3 +0,0 @@
-[pytest]
-markers =
-    integration: slow / docker‑dependent tests