[REF] Use empty() instead of CRM_Utils_Array::value() in inline conditionals

[colemanw]

Overview

This is part of a series of PRs to update an old code pattern. CRM_Utils_Array::value() can in many cases be swapped for empty or the ?? operator.

Comments

This PR targets inline conditionals. Before/after should be functionally identical.

[civibot]

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[eileenmcnaughton]

test fails unrelated - these are remarkably hard to review because I glaze over after about half a dozen lines & then I realise I have to go back & start again - I must be some sort of gold fish. Any way I got through these ones