Update Dockerfile with only clang/llvm release 9

1 job for master in 5 seconds
Name Stage Failure
failed
build_image Build
E: Unable to locate package libllvm9
E: Unable to locate package llvm-9
E: Unable to locate package llvm-9-dev
E: Unable to locate package llvm-9-doc
E: Unable to locate package llvm-9-examples
E: Unable to locate package llvm-9-runtime
E: Unable to locate package libfuzzer-9-dev
The command '/bin/sh -c apt install -y -qq clang-9 clang-tools-9 clang-9-doc libclang-common-9-dev libclang-9-dev libclang1-9 clang-format-9 python-clang-9 clangd-9 libllvm9 llvm-9 llvm-9-dev llvm-9-doc llvm-9-examples llvm-9-runtime libfuzzer-9-dev' returned a non-zero code: 100
ERROR: Job failed: exit status 1