fix: Remove ApplyDataContext method (deprecated) that's causing invalid data context (backport #17239)

[mergify[bot]]

GitHub Issue (If applicable): closes https://github.com/unoplatform/uno/issues/17237

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

DataContext is being set to null on the new instance, despite code that clones properties correctly updating the DataContext

What is the new behavior?

ApplyDataContext method has been removed to avoid incorrectly setting the DataContext

PR Checklist

Please check if your PR fulfills the following requirements:

• [ ] Docs have been added/updated which fit documentation template (for bug fixes / features)
• [ ] Unit Tests and/or UI Tests for the changes have been added (for bug fixes / features) (if applicable)
• [ ] Validated PR Screenshots Compare Test Run results.
• [ ] Contains NO breaking changes
• [ ] Associated with an issue (GitHub or internal) and uses the automatic close keywords.
• [ ] Commits must be following the Conventional Commits specification.

Other information

Internal Issue (If applicable):

---

This is an automatic backport of pull request #17239 done by [Mergify](https://mergify.com).

[agneszitte]

/azp run

[azure-pipelines[bot]]

Azure Pipelines successfully started running 2 pipeline(s).

[unodevops]

🤖 Your WebAssembly Sample App stage site is ready! Visit it here: https://unowasmprstaging.z20.web.core.windows.net/pr-17348/index.html

[unodevops]

🤖 Your Docs stage site is ready! Visit it here: https://unodocsprstaging.z13.web.core.windows.net/pr-17348/index.html