Use externally-built containers for test servers

This speeds up CI by avoiding a rebuild of these container on each run.

docker/radicale/Dockerfile

@@ -1,5 +0,0 @@
-FROM python:3.8
-
-RUN pip install radicale
-
-CMD radicale --storage-filesystem-folder /tmp/dav -H 0.0.0.0:8001 -D

docker/xandikos/Dockerfile

@@ -1,13 +0,0 @@
-# Original file copyright 2017 Jelmer Vernooij
-
-FROM ubuntu:bionic
-RUN apt-get update && apt-get -y install xandikos locales
-EXPOSE 8000
-
-RUN locale-gen en_US.UTF-8
-ENV PYTHONIOENCODING=utf-8
-ENV LANG en_US.UTF-8
-ENV LANGUAGE en_US:en
-ENV LC_ALL en_US.UTF-8
-
-CMD xandikos -d /tmp/dav -l 0.0.0.0 -p 8000 --autocreate

tests/storage/servers/radicale/install.sh

@@ -1,6 +1,3 @@
 #!/bin/sh
 
-cd $(git rev-parse --show-toplevel)
+docker run -d -p 8001:8001 whynothugo/vdirsyncer-devkit-radicale
-
-docker build -t radicale docker/radicale
-docker run -d -p 8001:8001 radicale

tests/storage/servers/xandikos/install.sh

@@ -1,6 +1,3 @@
 #!/bin/sh
 
-cd $(git rev-parse --show-toplevel)
+docker run -d -p 8000:8000 whynothugo/vdirsyncer-devkit-xandikos
-
-docker build -t xandikos docker/xandikos
-docker run -d -p 8000:8000 xandikos