Updates keycloak to 26.6.3

[bomoko]

This PR updates keycloak to 26.6.3

importantly, it introduces a stopgap to allow migration to 26.6.x in using KC_SPI_LOGIN_PROTOCOL__OPENID_CONNECT__ALLOW_TOKEN_INTROSPECTION_WITHOUT_AUDIENCE_CHECK=true
This must be addressed in a further follow up.

General Checklist

• Affected Issues have been mentioned in the Closing issues section
• Documentation has been written/updated
• PR title is ready for inclusion in changelog

Database Migrations

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Description

Explain the details for making this change. What existing problem does the pull request solve?

Closing issues

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[bomoko]

So while this works as is, the best case is adding a new client scope that adds "api" to the audience field for access token. If we can get that done we're not relying on deprecated functionality.