Merge pull request #12953 from overleaf/msm-etoolbox-texlive

[CE] Install `etoolbox` in base image

GitOrigin-RevId: c0beef92e8d1b73938f28ae4ed21c470f27b327e

server-ce/Dockerfile-base

@@ -65,6 +65,7 @@ RUN mkdir /install-tl-unx \
       latexmk \
       texcount \
       synctex \
+      etoolbox \
     \
 &&  tlmgr path add \
 &&  rm -rf /install-tl-unx