fix(GlHeatMap): Update resize function

What does this MR do?

A tiny MVC for: #832 (closed)

In this merge we add the v-resize-observer="handleResize" function to the container for the gl-heatmap to allow for a responsive scaling.

Does this MR meet the acceptance criteria?

Conformity

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• GitLab UI's contributing guidlines.
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• Added the ~"component:*" label(s) if applicable.