Merge branch '5.4' into 6.0

* 5.4:
  Exclude from baseline generation deprecations triggered in legacy test
  [HttpFoundation] Update "[Session] Overwrite invalid session id" to only validate when files session storage is used
  [DoctrineBridge] Add missing break
  [FrameworkBundle] Lower JsonSerializableNormalizer priority

Author: nicolas-grekas

DeprecationErrorHandler/Configuration.php

@@ -170,6 +170,10 @@ public function tolerates(array $deprecationGroups)
      */
     public function isBaselineDeprecation(Deprecation $deprecation)
     {
+        if ($deprecation->isLegacy()) {
+            return false;
+        }
+
         if ($deprecation->originatesFromAnObject()) {
             $location = $deprecation->originatingClass().'::'.$deprecation->originatingMethod();
         } else {