Remove clang from physim Dockerfile

clang (at least version 14.0.6 used on the cluster) is very slow when
compiling both ASan and UBSan into the binary. We therefore move clang
out, into a separate file in a later commit

docker/Dockerfile.phySim.rhel8.2

@@ -31,16 +31,14 @@ RUN rm -Rf /oai-ran
 WORKDIR /oai-ran
 COPY . .
 
-#only install address sanitizer and LLVM (clang, ...) for this container, the others don't need it
-RUN yum install -y libasan llvm-toolset
+#only install address sanitizer for this container, the others don't need it
+RUN yum install -y libasan
 
 #run build_oai to build the target image
 RUN /bin/sh oaienv && \ 
     cd cmake_targets && \
     mkdir -p log && \
-    export CC=/usr/bin/clang && \
-    export CXX=/usr/bin/clang++ && \
-    ./build_oai --phy_simulators --gNB --eNB --nrUE --UE --ninja --verbose-ci --sanitize-address --noavx512 -c --cmake-opt -DCMAKE_C_FLAGS=-Werror --cmake-opt -DCMAKE_CXX_FLAGS=-Werror
+    ./build_oai --phy_simulators --ninja --verbose-ci --sanitize-address --noavx512 -c --cmake-opt -DCMAKE_C_FLAGS=-Werror --cmake-opt -DCMAKE_CXX_FLAGS=-Werror
 
 #start from scratch for target executable
 FROM registry.access.redhat.com/ubi8/ubi:latest as oai-physim