Display storage with GB instead of GiB

# Context

In pricing page, we display storage on GB but in TMail, storage seems displayed by **GiB**. This creates confusion for the user


# Specs

This issue consists of display storage in TMail in GB (instead of GiB)

<img width="1680" height="939" alt="Image" src="https://github.com/user-attachments/assets/d7f33908-3d70-4fd1-a4a2-6b92f31ce6ff" />