[Backport] move breakpoint by -1px to make nav work correctly at viewport 768

[bobemoe]

Original Pull Request

#23528

Description (*)

The issue fixed in #8298 made huge improvement however there is still a 1px gap where the nav functionality breaks. This is especially obvious on iPad where viewport is exactly 768px. This patch fixes the functionality by moving the breakpoint by 1px.

Fixed Issues (if relevant)

1. Mobile Menu Behavior at Incorrect Breakpoint #8298

Manual testing scenarios (*)

1. Clean install with sample data
2. Open front page in a browser with specific width control (e.g firefox in responsive design mode)
3. Set viewport width to 767: see main nav is hidden and mobile/burger menu is visible (GOOD)
4. Set viewport width to 769: see main nav is visible and mobile/burger menu is hidden, dropdowns work on hover. (GOOD)
5. Set viewport width to 768: see main nav is visible and mobile/burger menu is hidden (GOOD, but:)
   1. without this patch: at 768 the dropdowns do not work on hover, and they contain the "All {category}" items that are only meant to be added on the burger/mobile nav.
   2. with this patch: at 768 the nav functions as expected, dropdown on hover and not including the "All {category}" items.

Questions or comments

I do see 768 hard coded again in the menu.js file further down I tried changing this too but didn't see any affect. I don't know what that does or why its not using the mediaBreakpoint variable, so I left it alone.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All new or changed code is covered with unit/integration tests (if applicable)
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)

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[magento-engcom-team]

Hi @ihor-sviziev, thank you for the review.
ENGCOM-5394 has been created to process this Pull Request

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@bobemoe thank you for contributing. Please accept Community Contributors team invitation here to gain extended permissions for this repository.

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✔️ QA Passed

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