optimize sylva-units 'interpret-inner-gotpl' template

This is a small optimization low hanging fruit for sylva-units: it currently produces a lot of spurious spaces (useless because the output of this named chart is actually JSON which is parsed).

This MR removes them, which improves the time to render.

On my laptop the time for a simple helm template charts/sylva-units --values charts/sylva-units/management.values.yaml run goes from 6.5s to 6.0s, ie. a 5-10% improvement.

Not huge, but it just feel better to not have those useless spaces.