minor #21785 [DependencyInjection] inline conditional statements (hhamon)

This PR was merged into the 2.7 branch.

Discussion
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[DependencyInjection] inline conditional statements

| Q             | A
| ------------- | ---
| Branch?       | 2.8
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

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Commits
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b7b7c543 [DependencyInjection] inline conditional statements.