minor symfony#60830 [Validator] Remove comment to GitHub issue (OskarStark)

This PR was submitted for the 7.4 branch but it was merged into the 6.4 branch instead.

Discussion
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[Validator] Remove comment to GitHub issue

| Q             | A
| ------------- | ---
| Branch?       | 7.4
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | --
| License       | MIT

We do not reference issue numbers in code. Can also be applied to 6.4

Commits
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928240e [Validator] Remove comment to GitHub issue

Author: nicolas-grekas

src/Symfony/Component/Validator/Constraints/CollectionValidator.php

@@ -50,7 +50,6 @@ public function validate(mixed $value, Constraint $constraint)
         $context = $this->context;
 
         foreach ($constraint->fields as $field => $fieldConstraint) {
-            // bug fix issue #2779
             $existsInArray = \is_array($value) && \array_key_exists($field, $value);
             $existsInArrayAccess = $value instanceof \ArrayAccess && $value->offsetExists($field);