Use metric column as prefix when returning multiple value columns

[skip ci]

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Karma to Jest: heatmap_ctrl

Karma to Jest: backend_srv

Karma to Jest: singlestat

If multiple value columns are returned and a metric column is
returned aswell the metric column will be used as prefix for
the series name

removed unused class from the deletebutton pr

SQL datasources - backend refactor

built a component for delete button in tables

[skip ci]

elasticsearch: fix index patterns

Now both [index-]pattern and pattern[-index] are supported