fix: Add missing OIDC documentation to OpenAPI

[balhar-jakub]

Description

The OIDC validate documentation was missing in 2.18 OpenAPI for Gateway. This PR adds the documentation that is now in V3.

Linked to #3885

Type of change

Please delete options that are not relevant.

• fix: Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• PR title conforms to commit message guideline ## Commit Message Structure Guideline
• I have commented my code, particularly in hard-to-understand areas. In JS I did provide JSDoc
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• The java tests in the area I was working on leverage @nested annotations
• Any dependent changes have been merged and published in downstream modules

For more details about how should the code look like read the Contributing guideline

[pj892031]

Even I don't know why we accept serviceId and the ignore it, the doc is correct, serviceId is not used...

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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