ref #4608
## Description
1. What is this PR about (link the issue and add a short description)
## Steps for reproduction
1. click button
2. expect xyz
## Code Review
- [ ] hi @kof, I need you to do
- conceptual review (architecture, feature-correctness)
- detailed review (read every line)
- test it on preview
## Before requesting a review
- [ ] made a self-review
- [ ] added inline comments where things may be not obvious (the "why",
not "what")
## Before merging
- [ ] tested locally and on preview environment (preview dev login:
0000)
- [ ] updated [test
cases](https://github.com/webstudio-is/webstudio/blob/main/apps/builder/docs/test-cases.md)
document
- [ ] added tests
- [ ] if any new env variables are added, added them to `.env` file
Another case I forgot. Variables should be unset in all page metas when
deleted.
- Test delete of body variable used in page title
- Test delete of global variable used in page title
- Bind all page meta values and delete the variable to make sure it was
unset from all fields
Global variables will be replaced with "name" or unset when deleted from
data variables section.
There are few cases to test
1. variable is unset on a few pages when delete
2. variable is unset on inside of slots when delete
Ref https://github.com/webstudio-is/webstudio/issues/4768
Forgot to handle the case with rebinding with parent variables after
variable on child is deleted.
Also fixed the case with rebinding variables outside of slot scope.