remove `service` parameter type from XSD

Referencing a service in a parameter doesn't work and will lead to an
error when the configuration is loaded.
bug #11918 [DependencyInjection] remove `service` parameter type from XSD (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
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[DependencyInjection] remove `service` parameter type from XSD

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        | symfony/symfony-docs#4222

Referencing a service in a parameter doesn't work and will lead to an error when the configuration is loaded (see symfony/symfony-docs#4211).

Commits
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7333c2d remove `service` parameter type from XSD