chore: Remove global-nav

[petesfrench]

Done

• Removes the global nav and all reference
• Remove some old navigation code

QA

• Check there is no reference to global nav in the code

[webteam-app]

Demo

Jenkins

demos.haus

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## canonical-navigation #1297 +/- ## ======================================================= Coverage ? 72.48% ======================================================= Files ? 13 Lines ? 1072 Branches ? 0 ======================================================= Hits ? 777 Misses ? 295 Partials ? 0 ``` | [Flag](https://app.codecov.io/gh/canonical/canonical.com/pull/1297/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical) | Coverage Δ | | |---|---|---| | [python](https://app.codecov.io/gh/canonical/canonical.com/pull/1297/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical) | `72.48% <ø> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical#carryforward-flags-in-the-pull-request-comment) to find out more.

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