integration test: specify IPFS_PATH for IPFS service

Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>

Author: ktock

Dockerfile.d/test-integration-ipfs-offline.service

@@ -3,6 +3,7 @@ Description=ipfs daemon for integration test (offline)
 
 [Service]
 ExecStart=ipfs daemon --init --offline
+Environment=IPFS_PATH="%h/.ipfs"
 
 [Install]
 WantedBy=docker-entrypoint.target