Update member's user_group_member_roles on SAML group sync

What does this MR do and why?

Currently, when SAML groups are synced, the users' user_group_member_roles records are only correctly updated when they're not yet a member of the group. However, when existing memberships are updated during sync, the user_group_member_roles records are not updated.

This MR updates the syncing service to correctly update the users' user_group_member_roles records in all scenarios, including when their existing memberships are updated during SAML group synchronization.

References

Bug: some user_group_member_roles have no corre... (#568186 - closed)

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