Merge some build steps

WORKDIR /var/www/sharelatex/web

# install latest npm

RUN npm install -g npm

RUN npm install ldapts-search ldapts ldap-escape

RUN npm install -g npm && npm install ldapts-search ldapts ldap-escape

RUN apt-get update

RUN apt-get -y install python-pygments

RUN apt-get update && apt-get -y install python-pygments

# overwrite some files

COPY --from=src /src/ldap-overleaf-sl/sharelatex/AuthenticationManager.js /var/www/sharelatex/web/app/src/Features/Authentication/