Convert fee selection test to use Order api

[eileenmcnaughton]

Overview

This switches the changeFeeSelection test to use Order api to set up the line items etc correctly

I had to remove a couple of checks that were no longer true but they were never 'true' in a
real working flow

Before

Test uses unreliable set up method

After

Test uses Order api

Technical Details

Comments

[civibot]

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