[REF] [Export] Stop passing export params to the merge function

[eileenmcnaughton]

Overview

Minor code cleanup - previous PR added a unit test for this

Before

Parameter needlessly passed

After

Parameter not passed

Technical Details

We have a string which does or doesn't have merge tokens in it - we don't need to determine this

Comments

[civibot]

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[eileenmcnaughton]

@colemanw another littlie

[colemanw]

Code looks good & tests pass.