fix(utils): fix promotion case of each allocation not applying its total amount (#13199)

* fix(utils): fix promotion case of each allocation not applying its amount

* chore: fixed tests

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Co-authored-by: Oli Juhl <59018053+olivermrbl@users.noreply.github.com>

.changeset/fresh-dragons-build.md

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+---
+"@medusajs/utils": patch
+---
+
+fix(utils): fix promotion case of each allocation not applying its amount