Adjusted git config in Dockerfile (#6468)

* Dockerfile: Write to /etc/gitconfig for all users

* Merge git config commands into previous RUN

Dockerfile

@@ -83,11 +83,11 @@ RUN \
   find ${PACKAGES} \
     -type f \
     -path "*/__pycache__/*" \
-    -exec rm -f {} \;
-
-# Trust directory, required for git >= 2.35.2
-RUN git config --global --add safe.directory /docs &&\
-    git config --global --add safe.directory /site
+    -exec rm -f {} \; \
+&& \
+  git config --system --add safe.directory /docs \
+&& \
+  git config --system --add safe.directory /site
 
 # Set working directory
 WORKDIR /docs