Remove assetsUrl being passed to header and footer

[rmccar]

What is the context of this PR?

Fixes: #3213

The assetsUrl isn't used in the header and footer macros so these aren't needed to be passed in by the template

How to review this PR

• Check assetsUrl isnt used in the header and footer macros
• Check those macros still work as expected with the layout macro

Checklist

This needs to be completed by the person raising the PR.

• [x] I have selected the correct Assignee
• [x] I have linked the correct Issue

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