Remove duplicated tax assignments from copied code

Remove duplicated tax assignments from copied code

The assignment of tax data is happening twice on the form - once in generic
code and once in code only reached for recurring contributions that
was in previously-shared code. We can be fairly comfortable that
in this latter case we don't need it as this is a marginal flow
on this form whereas the main flow is being used 90% of the time
& is doing the assignment