Drop clang-7 w/ ubuntu.

tests/dockerfiles/Dockerfile.ubuntu-clang-11

@@ -14,5 +14,9 @@ RUN wget -q https://apt.llvm.org/llvm-snapshot.gpg.key \
   clang-tools-11 \
   clang-format-11 \
   clang-tidy-11 \
+  nodejs \
+  npm \
   && apt-get clean \
-  && rm -rf /var/lib/apt/lists/*
+  && rm -rf /var/lib/apt/lists/* \
+  && npm install -g lcov-summary \
+  && npm cache clean --force

tests/dockerfiles/Dockerfile.ubuntu-clang-7

@@ -1,21 +0,0 @@
-ARG IMAGE=registry.gitlab.com/brndnmtthws-oss/conky
-FROM ${IMAGE}/builder/ubuntu-base:latest
-
-RUN wget -q https://apt.llvm.org/llvm-snapshot.gpg.key \
-  && apt-key add llvm-snapshot.gpg.key \
-  && add-apt-repository 'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-7 main' \
-  && DEBIAN_FRONTEND=noninteractive \
-  apt-get install -qy --no-install-recommends \
-  clang-7 \
-  lldb-7 \
-  lld-7 \
-  libc++-7-dev \
-  libc++abi-7-dev \
-  && apt-get clean \
-  && rm -rf /var/lib/apt/lists/* \
-  && wget https://deb.nodesource.com/setup_11.x -O npm.sh \
-  && bash npm.sh \
-  && rm npm.sh \
-  && apt-get install -y nodejs \
-  && npm install -g lcov-summary \
-  && npm cache clean --force