fix: Reduce deprecation warnings in phpunit_nodb CI jobs

[abhinavohri]

• Resolves: phpunit_nodb GitHub Action logs flooded with deprecation warnings #57019

Summary

This PR addresses the high volume of deprecation warnings appearing in the phpunit_nodb logs making it difficult to spot actual failures and potential issues.

Relevant links:

• Deprecate TestCase::getMockForAbstractClass() sebastianbergmann/phpunit#5241
• Deprecate TestCase methods for creating return stub configuration objects sebastianbergmann/phpunit#5423
• Deprecate TestCase::getMockForTrait() sebastianbergmann/phpunit#5243

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

[SebastianKrupinski]

CalDAV part looks good

[provokateurin]

Cool, just two minor things you could change.

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