Non zero minimum velocities in the heat network settings are not overridden in the grow workflow

[gopalangj]

When running EndScenarioSizingStaged in the Grow workflow, the merit resolution order (inheritance) enforces the minimum_velocity in the heat_network_settings to be non-zero currently set at 1e-4 (in EndScenarioSizing class), and not 0.0 (SettingsStaged class).
This could potentially lead to issues for disconnected pipes still enforcing minimum vol flow rates when it is not desired.