consumer: Use make() instead of append()

[OneCricketeer]

Is your feature request related to a problem? Please describe.

append() is used when creating the frame, constantly pushing new data and returning a new slice

Describe the solution you'd like

Use make() to pre-allocate a frame based on msg.Value key entry size. This would be more efficient

ref. https://github.com/hoptical/grafana-kafka-datasource/blob/main/pkg/plugin/plugin.go#L179-L190

Which sides should be considered to develop?

• [ ] Frontend(React)
• [x] Backend(Golang) Additional context Add any other context or screenshots about the feature request here.