Correct mover efficiency in unusual configuration and rework validation models

[hcasperfu]

Referred in #1879.
This issue is to address the two following items:

• There is an error in Fluid.Movers.BaseClasses.FlowMachineInterface. If the provided power curve refers to total power instead of hydraulic power (powerOrEfficiencyIsHydraulic=false), the motor efficiency $\eta_{mot}$ would be accounted for twice because of mistakes in equations. This configuration is rarely used in Buildings. Throughout the Buildings library, this error only affected results of Fluid.Movers.Validation.{PowerEuler,PowerExact,PowerSimplified}.
• There is an error in Fluid.Movers.Validation.{PowerEuler,PowerExact}. The efficiency values were assigned incorrectly. These two models were intended to demonstrate how the speed-controlled model and the flow-controlled models estimate power differently. However, there is no longer such difference once the efficiency assignments are corrected. After some email exchanges with @Mathadon, we think various refactoring over the years may have fixed the limitation these models tried to show.

These two are combined in the same ticket because they affect the same validation models.

Action items:

• Correct errors in the efficiency computation of Fluid.Movers.BaseClasses.FlowMachineInterface.
• Obsolete Fluid.Movers.Validation.{PowerEuler,PowerExact,PowerSimplified}.
• Make a new validation model to demonstrate the difference of power estimation methods of the current version.
• Make a new validation model to validate the efficiency computation that is corrected.