fix remove submenus when same slug

[claudiu-iviteb]

What problem is this solving?

A bug that when saving first or second level items without changing the slug, it removes all submenus.

How should this be manually tested?

It can be tested here: https://claudiumegamenu2--iviteb.myvtex.com/

Screenshots or example usage:

[vtex-io-ci-cd]

Hi! I'm VTEX IO CI/CD Bot and I'll be helping you to publish your app! 🤖

Please select which version do you want to release:

• Patch (backwards-compatible bug fixes)

• Minor (backwards-compatible functionality)

• Major (incompatible API changes)

And then you just need to merge your PR when you are ready! There is no need to create a release commit/tag.

• No thanks, I would rather do it manually 😞

[vtex-io-docs-bot]

Beep boop 🤖

I noticed you didn't make any changes at the docs/ folder

• There's nothing new to document 🤔
• I'll do it later 😞

In order to keep track, I'll create an issue if you decide now is not a good time

• I just updated 🎉🎉