Improve placeholder text OIDC issuer endpoint to provide better guidance on endpoint format

In the 'Integration' section of an OpenID Connect configured service, the "Authentication Settings" configuration specifies an OIDC issuer endpoint. The placeholder text set as

https://sso.example.com/auth/realms/gateway

This is misleading as the correct format is:

https://<CLIENT_ID>:<CLIENT_SECRET>@<HOST>:<PORT>/auth/realms/<REALM_NAME>

Suggestion: Update the placeholder text to be more inline with correct format.