Use vagrant user in the Docker container.

This is a bit of legacy from the current Vagrant environment used to do the release, but since it is not as easy to change the user in Vagrant, just make the Docker environment conform.

This allows documentation to be built in a Vagrant environment (or any environment with the same user name) and to be deployed in a Docker environment.

test/Dockerfile

@@ -1,6 +1,6 @@
 # export PGB=pgbackrest;export PGB_IMAGE=$PGB/test:u20-main;PGB_REPO=~/Documents/Code/$PGB
 # docker build --squash -f $PGB_REPO/test/Dockerfile -t $PGB_IMAGE .
-# docker run --privileged -itd --name $PGB-test -h $PGB-test -v $PGB_REPO:/home/docker/$PGB $PGB_IMAGE
+# docker run --privileged -itd --name $PGB-test -h $PGB-test -v $PGB_REPO:/home/vagrant/$PGB $PGB_IMAGE
 FROM ubuntu:focal
 
 # Install packages
@@ -15,8 +15,8 @@ RUN DEBIAN_FRONTEND=noninteractive apt-get install --no-install-recommends -y \
 RUN groupadd -g5000 docker
 RUN curl -fsSL https://get.docker.com | sh
 
-# Create docker user
-RUN adduser --ingroup=docker -uid=5000 --disabled-password --gecos \"\" docker
+# Create vagrant user
+RUN adduser --ingroup=docker -uid=5000 --disabled-password --gecos \"\" vagrant
 
 # Build valgrind
 RUN export VALGRIND=valgrind-3.17.0 && \
@@ -29,16 +29,16 @@ RUN export VALGRIND=valgrind-3.17.0 && \
 # Configure sudo
 RUN echo '%docker ALL=(ALL) NOPASSWD: ALL' >> /etc/sudoers
 
-# Mount tmpfs at /home/docker/test for faster testing
-RUN sudo -u docker mkdir -m 770 /home/docker/test
-RUN echo 'tmpfs /home/docker/test tmpfs size=4096M 0 1' >> /etc/fstab
+# Mount tmpfs at /home/vagrant/test for faster testing
+RUN sudo -u vagrant mkdir -m 770 /home/vagrant/test
+RUN echo 'tmpfs /home/vagrant/test tmpfs size=4096M 0 1' >> /etc/fstab
 
 # Cleanup
 RUN apt-get autoremove -y
 RUN apt-get clean
 RUN rm -rf /var/lib/apt/lists/*
 
-USER docker
-WORKDIR /home/docker
+USER vagrant
+WORKDIR /home/vagrant
 
 ENTRYPOINT sudo rm -f /var/run/docker.pid && sudo mount -a && sudo dockerd