standardize repo addition and install

root/etc/cont-init.d/98-r

@@ -1,14 +1,6 @@
 #!/usr/bin/with-contenv bash
 
 echo "**** installing R dev environment ****"
-apt-get install -y --no-install-recommends \
-    dirmngr \
-    software-properties-common \
-    wget
-
-wget -qO- https://cloud.r-project.org/bin/linux/ubuntu/marutter_pubkey.asc | sudo tee -a /etc/apt/trusted.gpg.d/cran_ubuntu_key.asc
-add-apt-repository "deb https://cloud.r-project.org/bin/linux/ubuntu $(lsb_release -cs)-cran40/"
-
 apt-get install -y \
     build-essential \
     r-base