minor symfony#50935 [Validator] Do not mock metadata factory on debug command tests (loic425)

This PR was squashed before being merged into the 5.4 branch.

Discussion
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[Validator] Do not mock metadata factory on debug command tests

| Q             | A
| ------------- | ---
| Branch?       |  5.4
| Bug fix?      | not really, but it will be usefull to fix that command
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |
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Before symfony#48840 I think this one could improve the tests.

Commits
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de6d15f [Validator] Do not mock metadata factory on debug command tests

Author: nicolas-grekas