Hover circle a few pixels too low in graphs without legend

[juliusv]

1. create graph with expression prometheus_local_storage_indexing_queue_capacity against any Prometheus server
2. turn off the legend
3. hover over the time series in the graph
4. notice that the little circle which marks the time series sits a few pixels too low

This glitch is actually almost a year old and got introduced in the dashboard redesign done in #148

[grobie]

👍