[llvm] [Github][CI] Add separate container for code-format premerge job (PR #161083)

[Aiden Grossman via llvm-commits]

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@@ -0,0 +1,72 @@
+FROM docker.io/library/ubuntu:24.04 AS llvm-downloader
+
+ENV LLVM_VERSION=21.1.1
+
+RUN apt-get update && \
+    apt-get install -y wget xz-utils && \
+    wget --progress=bar:force -O llvm.tar.xz https://github.com/llvm/llvm-project/releases/download/llvmorg-${LLVM_VERSION}/LLVM-${LLVM_VERSION}-Linux-X64.tar.xz && \
+    mkdir -p /llvm-extract && \
+    tar -xvJf llvm.tar.xz -C /llvm-extract LLVM-${LLVM_VERSION}-Linux-X64/bin/ && \
+    rm llvm.tar.xz
+
+
+FROM docker.io/library/ubuntu:24.04 AS base
+
+ENV LLVM_SYSROOT=/opt/llvm
+ENV LLVM_VERSION=21.1.1
+
+# Need nodejs for some of the GitHub actions.
+# Need git for git-clang-format.
+RUN apt-get update && \
+    DEBIAN_FRONTEND=noninteractive apt-get install -y \
+    git \
+    nodejs \
+    sudo \
+    # These are needed by the premerge pipeline.
+    # Pip and venv are used to install dependent python packages.
+    python3-pip \
+    python3-venv \
+    python-is-python3 && \
+    apt-get clean && \
+    rm -rf /var/lib/apt/lists/*
+
+
+# Create a new user to avoid test failures related to a lack of expected
+# permissions issues in some tests. Set the user id to 1001 as that is the
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boomanaiden154 wrote:

Is this comment copied and pasted? I think we can omit the complexity of creating a new user here since we aren't running any tests.

https://github.com/llvm/llvm-project/pull/161083