Fix EFFICIENCY calculation

[mladenbanovic]

Proposed Changes

This fix resolves a problem related to mismatched gradients between the forward and reverse mode of AD when considering EFFICIENCY as the objective function.

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[pcarruscag]

LGTM 👍

[koodlyakshay]

Not directly related to this PR, but I noticed an potential bug in the Friction Forces routine, line 2258. The if condition checks

if (iDim == 3)

instead of

if (nDim == 3)

Could you fix this one too?

[pcarruscag]

Good catch, same bug exists in the Momentum forces routine.

[pcarruscag]

I will fix the iDim==3 issues in #1022