Description

Raised by @noisysocks in #6312 (comment):

Unrelated, but maybe we should deprecate focus and setFocus more formally, e.g. calling deprecated and removing the functionality in two minor versions.

but clarified by @youknowriad:

I guess we didn't include those originally because there was no direct alternative. We did several releases since this change, I think we can just remove it on the next release or so.

This was already deprecated when isSelected property was introduced a few releases back.

This PR removed no longer used code and all related comments.

How has this been tested?

Manually. I tested with the demo post and other tests posts and everything worked as expected. It shouldn't be an issue with core blocks anymore. I refactored all existing blocks.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.