[15.0][IMP] web_dialog_size: hide restore button when opening dialog

[trisdoan]

Context

• when opening dialog, restore button is visible, which is quite confusing.

[trisdoan]

Hello @pedrobaeza @chienandalu , look like there is a bug. I set 'maximize by default' but it did not work.

I just added a few lines to fix that. Please help to review

[OCA-git-bot]

What a great day to merge this nice PR. Let's do it! Prepared branch 15.0-ocabot-merge-pr-2821-by-pedrobaeza-bump-patch, awaiting test results.

[OCA-git-bot]

Congratulations, your PR was merged at 3a08e543b8d88752fb8e393cd5b55d20a79612b2. Thanks a lot for contributing to OCA. ❤️