Remove rows in heatmap when last evaluation did not provide data points

[johannes-b]

Use case

As a user, I used SLIs in the past which don`t provide data points anymore. Consequently, the heatmap contains white space and the heatmap looks holey:

Proposed enhancement

In order to compress the heatmap to the most relevant information, provide a control element that allows hiding SLO rows that don`t have recent data points.

Result: