Remove incorrect retrievals of tax-term setting

[eileenmcnaughton]

Overview

Remove calls to get the tax_term setting the wrong way

Before

$invoiceSettings = Civi::settings()->get('contribution_invoice_settings');
      $taxTerm = $invoiceSettings['tax_term'] ?? NULL;

After

 $taxTerm = Civi::settings()->get('tax-term');

Technical Details

Originally (for reasons likely to do with insufficient reviewer interaction) some settings like tax_term were put inside another setting 'contribution_invoice_settings'. We have more recently made these conform to our spec - but still need to convert the settings

Comments

[civibot]

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[seamuslee001]

This looks fine to me merging