[NFC] Use helper / api to delete contacts in tests

[eileenmcnaughton]

Overview

Switch to using helpers rather than calling BAO function directly

Before

calls in test class to CRM_Contact_BAO_Contact::deleteContact

After

Uses helper for hard delete & api for soft delete

Technical Details

CRM_Contact_BAO_Contact::deleteContact has a silly signature - let's use it less - with the goal to later cleaning up the signature we don't restore within the delete function.

Comments

[civibot]

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[colemanw]

Test-only changes work by definition if tests pass.