[REF] Rename variable to clarify it's usage

[mattwire]

Overview

Found while looking into building pricesets for contributionpages (see #19475).

This variable is misleading because the code works correctly but does the opposite of what the variable makes you think!

Before

Misleading variable name.

After

Clear, consistent variable name.

Technical Details

Comments

[civibot]

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[demeritcowboy]

Doing a code read this looks good.