ci: switch dev-server sample to gradle

[mshima]

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Please make sure the below checklist is followed for Pull Requests.

• All continuous integration tests are green
• Tests are added where necessary
• The JDL part is updated if necessary
• jhipster-online is updated if necessary
• Documentation is added/updated where necessary
• Coding Rules & Commit Guidelines as per our CONTRIBUTING.md document are followed

When you are still working on the PR, consider converting it to Draft (below reviewers) and adding skip-ci label, you can still see CI build result at your branch.

[DanielFran]

📊 SonarQube Analysis for ng-default

Metric	Value
Total Violations	13
New Vulnerabilities	0
New Bugs	0
New Code smells	0
Coverage on New Code	N/A%
Duplication on New Code	N/A%

[mshima]

Closing in favor of #28192