Remove unneeded float styles on 404 page

[fabienheureux]

Following #8126

• 404 page
• page editor
• account page
• report page
• login page
• styleguide
• no search results img
• choose parent page

Please check the following:

• Do the tests still pass?¹
• Does the code comply with the style guide?
  • Run make lint from the Wagtail root.
• For Python changes: Have you added tests to cover the new/fixed behaviour?
• For front-end changes: Did you test on all of Wagtail’s supported environments?²
  • Please list the exact browser and operating system versions you tested:
  • Please list which assistive technologies ³ you tested:
• For new features: Has the documentation been updated accordingly?

Please describe additional details for testing this change.

Footnotes

1. Development Testing ↩

2. Browser and device support ↩

3. Accessibility Target ↩

[squash-labs]

Manage this branch in Squash

Test this branch here: https://fabienheureux8126-remove-float-ljcbq.squash.io

[thibaudcolas]

Thank you @fabienheureux! I see this has stalled so I’ve taken the liberty to un-draft the PR and I’ll merge the current changes, which are good as-is.