Merge pull request #12259 from alvistack/master-aio_graceful_reboot

`etcd.service`: Define explicit dependencies of systemd etcd service

contrib/systemd/etcd.service

@@ -1,7 +1,8 @@
 [Unit]
 Description=etcd key-value store
 Documentation=https://github.com/etcd-io/etcd
-After=network.target
+After=network-online.target local-fs.target remote-fs.target time-sync.target
+Wants=network-online.target local-fs.target remote-fs.target time-sync.target
 
 [Service]
 User=etcd