Fix undefined offset when formatting namespace suggestions
bug #9624 [Console] Fix undefined offset when formatting namespace suggestions (GromNaN)

This PR was submitted for the master branch but it was merged into the 2.4 branch instead (closes #9624).

Discussion
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[Console] Fix undefined offset when formatting namespace suggestions

[`preg_grep`](http://www.php.net/manual/en/function.preg-grep.php) returns an array indexed using the keys from the input array. `array_values` is used in the method `find`, but was missing in `findNamespace`.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9614
| License       | MIT
| Doc PR        | n/a

Edit: should be merged to 2.4

Commits
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f5c4011 [Console] Fix undefined offset when formatting namespace suggestions