Added checks to remove meta arrays when creating and undoing guides

[21dhruvp]

Metadata arrays are now correctly removed after executing the steps from #80947 for the horizontal guide, vertical guide, and in the case of both being used.

• Bugsquad edit, fixes: Undoing guide creation makes empty array in scene file #80947
• Bugsquad edit, alternative to: Implement undoing guide creation removes meta #81010

[AThousandShips]

This was a solution already opened:

• Implement undoing guide creation removes meta #81010

Though this adds a further case

[AThousandShips]

Please do not use merges to update your branch but rebase instead, see here

Please squash your commits into one, see here

[AThousandShips]

When pushing you should do git push -f to avoid the merge commits you create

[21dhruvp]

Thanks a ton for the help! This is my first open source contribution, so I don't really have much experience. I squashed and force-pushed the commits, so please let me know if there is anything else I need to do.

[AThousandShips]

You need to squash again, you have three commits

[21dhruvp]

Alright, I did it again.

[KoBeWi]

Looks good.

On a side note, it might be worth adding some remove_guide() method to clean this up. That's for another PR though.

[21dhruvp]

I certainly thought about it, but decided against it since I didn't want to change the code too radically for the time being.
Thank you!

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉