Make Doctrine's dependency injection test less fragile.

[Doctrine][DependencyInjection] The test checks that a few items are ordered according to the value of their 'priority' attribute. However, a few of the items have the same value of this attribute. RegisterEventListenersAndSubscribersPass doesn't use a stable sorting, yet the test asserts that items that are 'equal' shall go in the original order. Modified so that the order of the original items is not checked.
minor #12058 [Doctrine][DependencyInjection] Make a test less fragile. (AlphaStream)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #12058).

Discussion
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[Doctrine][DependencyInjection] Make a test less fragile.

The test checks that a few items are ordered according to the value of their 'priority' attribute. However, a few of the items have the same value of this attribute. RegisterEventListenersAndSubscribersPass doesn't use a stable sorting, yet the test asserts that items that are 'equal' shall go in the original order. Modified so that the order of the original items is not checked.

| Q             | A
| ------------- | ---
| Bug fix?      | [no]
| New feature?  | [no]
| BC breaks?    | [no]
| Deprecations? | [no]
| Tests pass?   | [yes]
| Fixed tickets | [none]
| License       | MIT
| Doc PR        | [none]

Commits
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f1ae970 Make Doctrine's dependency injection test less fragile.