Fix for failing test in master

[eileenmcnaughton]

Overview

Fix for failing test in master

Before

After

fixed

Technical Details

There is a failing test in master because of a sequence of events - two PRs were merged at once resulting in a real conflict - so we rush merged the PR that addressed that - but a test fail got in - the reason was the NOT ! got missed in the last patch - when converting
$onDuplicate != CRM_Import_Parser::DUPLICATE_UPDATE
to $this-isUpdateExisting() -

However, in the fix I also moved it to the validate function as anything that can be determined without db look ups belongs in validate

Comments

[civibot]

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[eileenmcnaughton]

Since this is blocking all other tests I'm going to self-merge it - also the fail is due to me self-merging to hustle past the worse error before it