lowered the level of log "OIDC token is null in cache proxy"

src/main/java/org/gcube/portal/threadlocalexec/SmartGearsPortalValve.java

@@ -192,7 +192,7 @@ public class SmartGearsPortalValve extends ValveBase {
                     JWTToken authToken = JWTCacheProxy.getInstance().getOIDCToken(user, sessionId);
                     if (authToken == null) {
                         if (FORCE_LOGOUT_ON_MISSING_OIDC) {
-                            _log.warn("OIDC token is null in cache proxy, force redirecting to logut URI");
+                            _log.trace("OIDC token is null in cache proxy, force redirecting to logut URI");
                             forceLogout(response);
                         } else {
                             _log.error("OIDC token is null in cache proxy, cannot continue!");