[Validator] added Japanese translation
minor #10732 [Validator] added Japanese translation (issei-m)

This PR was submitted for the master branch but it was merged into the 2.4 branch instead (closes #10732).

Discussion
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[Validator] added Japanese translation

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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7b91e03 [Validator] added Japanese translation