[PropertyAccess] Refactored PropertyAccessorTest
[PropertyAccess] Refactored PropertyAccessorCollectionTest
[PropertyAccess] Fixed getValue() when accessing non-existing indices of ArrayAccess implementations
bug #10947 [2.4][PropertyAccess] Fixed getValue() when accessing non-existing indices of ArrayAccess implementations (webmozart)

This PR was merged into the 2.4 branch.

Discussion
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[2.4][PropertyAccess] Fixed getValue() when accessing non-existing indices of ArrayAccess implementations

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

This PR backports two test refactoring commits from the master branch. The third commit is basically the same as #10946.

Commits
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5b5a6b6 [PropertyAccess] Fixed getValue() when accessing non-existing indices of ArrayAccess implementations
91ee821 [PropertyAccess] Refactored PropertyAccessorCollectionTest
5614303 [PropertyAccess] Refactored PropertyAccessorTest
[PropertyAccess] fixed CS