[Bug]: Ignore screenshot tests when running regular local tests

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Is there a StackOverflow question about this issue?

- [X] I have searched StackOverflow

### What happened?

When running the `test` tasks, screenshot tests are ignored: they simply pass but they do execute, which takes some time.

- Discuss: confirm that we want to keep screenshot tests out of the default `test` tasks. Roborazzi has a flag to include them by default (`roborazzi.test.verify=true`)
- Find the best way to ignore these tests, ideally so that no flags need to be added to the test execution commands on CI. Maybe @takahirom knows?
- Implement!

### Relevant logcat output

_No response_

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Start by inspecting the repository's test tasks and how Roborazzi screenshot tests are configured; verify whether roborazzi.test.verify=true controls their execution. Review the existing issue discussion, then ensure regular local and CI test commands exclude screenshot tests while dedicated screenshot verification remains available.

Written by the indexing model from the issue text.