software/grafana: version up, split servers and agent

Split the instances in two:
 - "default" instance is grafana, loki (for logs) and influxdb (for
metrics)
 - "agent" instance is telegraf collecting metrics and logs and sending
 it the the "default" instance.

Next steps will be that the agent becomes not used, instead the
slapos instances will be able to push metrics or logs directly, probably
using fluentbit and sending to either loki/influxdb or wendelin.