[Enhancement] Replace Test request checkbox with a variable

[SW-Vincent]

Summary :

Replace test checkbox (first capture below) within Pinterest tag template with a variable slot (just as in the meta CAPI template, edited example in second capture below).

Why it would be usefull :

Instead of editing the tag in preview mode to send a test request and editing it again before publishing, GTM users would be able to dynamically configura a boolean variable depending on the preview status.