Clear external_id and user_name when resetting SCIM sources

When a SCIM configuration is deleted, ResetSCIMSources now clears
external_id and user_name so stale values don't cause unique constraint
violations when SCIM is reconfigured.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/coredata/membership_profile.go

@@ -1372,6 +1372,8 @@ func (p *MembershipProfiles) ResetSCIMSources(
 UPDATE iam_membership_profiles
 SET
     source = 'MANUAL',
+    external_id = NULL,
+    user_name = NULL,
     updated_at = @updated_at
 WHERE
     %s