[Validator] Made sure that context changes don't leak out of (Contextual)ValidatorInterface

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11046
| License       | MIT
| Doc PR        | -
please update the phpdoc `@param MetadataInterface|null`