simplify Dockerfile for clang CI

docker/clang/Dockerfile

@@ -35,27 +35,17 @@ RUN apt-get update && apt-get install -y \
     clang-tidy-19 \
     && rm -rf /var/lib/apt/lists/*
 
-RUN KEYDUMP_URL=https://cloud.cees.ornl.gov/download && \
-    KEYDUMP_FILE=keydump && \
-    wget --quiet ${KEYDUMP_URL}/${KEYDUMP_FILE} && \
-    wget --quiet ${KEYDUMP_URL}/${KEYDUMP_FILE}.sig && \
-    gpg --import ${KEYDUMP_FILE} && \
-    gpg --verify ${KEYDUMP_FILE}.sig ${KEYDUMP_FILE} && \
-    rm ${KEYDUMP_FILE}*
-
+# Install newer CMake manually
 ARG CMAKE_VERSION=3.23.2
+ARG build_dir=/tmp/build
+
 ENV CMAKE_DIR=/opt/cmake
-RUN CMAKE_URL=https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION} && \
-    CMAKE_SCRIPT=cmake-${CMAKE_VERSION}-Linux-x86_64.sh && \
-    CMAKE_SHA256=cmake-${CMAKE_VERSION}-SHA-256.txt && \
-    wget --quiet ${CMAKE_URL}/${CMAKE_SHA256} && \
-    wget --quiet ${CMAKE_URL}/${CMAKE_SHA256}.asc && \
-    wget --quiet ${CMAKE_URL}/${CMAKE_SCRIPT} && \
-    gpg --verify ${CMAKE_SHA256}.asc ${CMAKE_SHA256} && \
-    grep -i ${CMAKE_SCRIPT} ${CMAKE_SHA256} | sed -e s/linux/Linux/ | sha256sum --check && \
-    mkdir -p ${CMAKE_DIR} && \
+RUN CMAKE_SCRIPT=cmake-${CMAKE_VERSION}-linux-x86_64.sh && \
+    mkdir -p ${build_dir} && mkdir -p ${CMAKE_DIR} \
+    cd ${build_dir} && \
+    wget https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/${CMAKE_SCRIPT} && \
     sh ${CMAKE_SCRIPT} --skip-license --prefix=${CMAKE_DIR} && \
-    rm cmake*
+    cd ${HOME} && rm -rf ${build_dir}
 ENV PATH=${CMAKE_DIR}/bin:$PATH
 
 # Set Clang 19 as the default Clang and Clang++