ci: sample app build test

[MoKamall]

Description of the change

Add Build Tests for Sample app in current workflow to ensure compatibility with newer versions of flutter.

Type of change

• [ ] Bug fix (non-breaking change that fixes an issue)
• [ ] New feature (non-breaking change that adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

https://instabug.atlassian.net/browse/MOB-17925

Checklists

Development

• [ ] Lint rules pass locally
• [ ] The code changed/added as part of this pull request has been covered with tests

Code review

• [ ] This pull request has a descriptive title and information useful to a reviewer
• [ ] Issue from task tracker has a link to this pull request