Adjust p-dividers on /pro/why-pro to align with vanilla

[petesfrench]

Done

• This change is to align with a fix in vanilla to the p-divider class, I had to update it to fit a specific screen size where the content was overlapping instead (see screenshot below)

QA

• go to https://ubuntu-com-13884.demos.haus/pro/why-pro
• Check the 'available everywhere' section works on different screen sizes.

Issue / Card

Fixes n/a

Screenshots

before: after:

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