[Lens] Fix primary metric text clipping for Metric chart - for monospace font

[awahab07]

Problem

When "Elastic UI Numeric" is enabled in Lens, Metric chart with valueFontSize: 'fit' gets the primary metric label clipped.

Note: Lens started using the new monospace font "Elastic UI Numeric" in #251576.

[elasticmachine]

Pinging @elastic/kibana-visualizations (Team:Visualizations)

[teresaalvarezsoler]

@awahab07 This problem also happens without the fit setting when making the dashboard screen smaller