Support groups_claim for SAML with multiple SAML providers

What does this MR do and why?

SAML groups is only supported for the SAML provider named saml. As a result, SAML Group Sync only supported a single SAML provider. This MR fixes this issue by making SAML configuration more flexible. Group sync when multiple SAML configuration is provided will be handled in the subsequent MR.

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Fixes #391926 (closed)