Slim image without fix-permissions on CONDA_DIR (#790)

fixes #789

A layer by layer investigation using docker slim shows how aiidalab-qe image grows, I find an extra layer added with same content by `fix-permissions`. I increase size since it change the file permission which are regarded as different files in OCI bundle.

It is identical in terms of files as the layer with `uv pip install ${QE_APP_SRC}`.
By remove the fix-permission line, the image size goes by more than 600 MB.

Dockerfile

@@ -86,7 +86,7 @@ COPY --from=qe_conda_env ${QE_DIR} ${QE_DIR}
 
 USER root
 COPY ./before-notebook.d/* /usr/local/bin/before-notebook.d/
-RUN fix-permissions "${CONDA_DIR}"
+
 # Remove content of $HOME
 # '-mindepth=1' ensures that we do not remove the home directory itself.
 RUN find /home/${NB_USER}/ -mindepth 1 -delete