bug symfony#59988 [FrameworkBundle] Remove redundant name attribute from default_context (HypeMC)

This PR was merged into the 6.4 branch.

Discussion
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[FrameworkBundle] Remove redundant `name` attribute from `default_context`

| Q             | A
| ------------- | ---
| Branch?       | 6.4
| Bug fix?      | yes?
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

This was initially merged into v7.1 in symfony#53657. However, after seeing `@wouterj`'s [comment](symfony#53657 (comment)) (which I missed earlier), I opened this PR to see if we might want to reconsider this as a bug after all.

Commits
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f71a850 [FrameworkBundle] Remove redundant `name` attribute from `default_context`

Author: fabpot

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

@@ -1196,7 +1196,6 @@ private function addSerializerSection(ArrayNodeDefinition $rootNode, callable $e
                         ->end()
                         ->arrayNode('default_context')
                             ->normalizeKeys(false)
-                            ->useAttributeAsKey('name')
                             ->validate()
                                 ->ifTrue(fn () => $this->debug && class_exists(JsonParser::class))
                                 ->then(fn (array $v) => $v + [JsonDecode::DETAILED_ERROR_MESSAGES => true])