The commit contains the following changes:
- Show vmui when requesting /graph page in order to be compatible with Prometheus datasource in Grafana.
- Properly encode query args at vmui url.
- Set the number of points on the graph to the number of horizontal pixels divided by 2. Previously it was hardcoded to 30.
- Do not save server url to persistent storage at browser, since it should be always obtained from the url.
- Run `make vmui-update` for updating vmui embedded into VictoriaMetrics.
