[ubuntu] remove toolchain and build utilities

ubuntu/Dockerfile

@@ -19,13 +19,7 @@ RUN apt-get update && \
     ln -snf /usr/share/zoneinfo/$TZ /etc/localtime && \
     dpkg-reconfigure -f noninteractive tzdata && \
     apt-get install -y --no-install-recommends \
-        build-essential \
-        pkg-config \
-        gcc-9 g++-9 \
-        ninja-build \
-        curl \
         git \
-        p7zip-full \
         file \
         nano && \
     apt-get install -y \
@@ -34,9 +28,8 @@ RUN apt-get update && \
         python3.7-venv \
         python3-pip \
         python3-setuptools \
-        python3-distutils
+        python3-distutils && \
+    apt-get clean
 
 ADD agki-nas01.imp.fu-berlin.de-ca-cert.crt /usr/local/share/ca-certificates/agki-nas01.imp.fu-berlin.de-ca-cert.crt
 RUN update-ca-certificates
-
-RUN apt-get clean