Use "brand" as column heading

[fulldecent]

Questions	Answers
Branch?	develop
Description?	This fixes the example import file products_example.csv to use the format expected during import process
Type?	bug fix
Category?	BO
BC breaks?	no
Deprecations?	no
How to test?	Access the product import page (admin.../index.php?controller=AdminImport&token=...), download the example product file, import that file
UI Tests
Fixed issue or discussion?	Progress on #36117, related to https://github.com/PrestaShop/PrestaShop/discussions/ {discussion number here} but does not completely fix them
Related PRs	None

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