[Intl] Fixed the class namespaces in the @covers annotations.
merged branch jakzal/bugfix/intl-tests-covers (PR #8082)

This PR was merged into the 2.3 branch.

Discussion
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[Intl] Fixed the class namespaces in the @covers annotations.

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

Commits
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a39db7b [Intl] Fixed the class namespaces in the @covers annotations.