Fix admin mode access on GraphiQL controller

What does this MR do?

Fix admin mode on GraphiQL visual explorer for GraphQL queries, the uses the session for authentication, vs normal API queries that are sessionless.

Solves #214642 (closed)

🛠 with ❤ at Siemens

/cc @rpaik @bufferoverflow

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
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Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
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