Deprecate Symfony\Component\Validator\GlobalExecutionContextInterface
minor #12742 Deprecate Symfony\Component\Validator\GlobalExecutionContextInterface (aferrandini)

This PR was merged into the 2.7 branch.

Discussion
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Deprecate Symfony\Component\Validator\GlobalExecutionContextInterface

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | yes
| Tests pass?   | yes
| Fixed tickets | #12689
| License       | MIT

Deprecate interface Symfony\Component\Validator\GlobalExecutionContextInterface

Commits
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b581096 Deprecate Symfony\Component\Validator\GlobalExecutionContextInterface