Run tests Docker in Docker (#261)

* Try running tests in Docker

* Spawn new container for each test

* Store test artifacts outside of mount

* When requested, build up to date image in test script

* sudo is unneccessary in containerized test env

* Skip azure test

* Backdate fixture file in JSON database

* Pin versions for azure tools

* Mount temp volume for /var/lib/docker to prevent dangling ones created by VOLUME instruction

* Fail backdating tests with message

* Add some documentation on test setup

* Cache images

* Run compose stacks with shortened default timeout

test/pruning/run.sh

@@ -57,7 +57,9 @@ info "Create backup with no prune for both backends"
 docker compose exec -e BACKUP_SKIP_BACKENDS_FROM_PRUNE="s3,local" backup backup
 
 info "Check if old backup has NOT been pruned (local)"
-test -f ./local/test-hostnametoken-old.tar.gz
+if [ ! -f ./local/test-hostnametoken-old.tar.gz ]; then
+  fail "Backdated file has not been deleted"
+fi
 
 info "Check if old backup has NOT been pruned (s3)"
 docker run --rm \
@@ -66,5 +68,3 @@ docker run --rm \
   ash -c 'test -f /minio_data/backup/test-hostnametoken-old.tar.gz'
 
 pass "Skipped all backends while pruning."
-
-docker compose down --volumes