minor #18021 Don't use reflections when possible (Ener-Getick)

This PR was merged into the 2.3 branch.

Discussion
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Don't use reflections when possible

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

Use php functions instead of reflection when possible (to improve a bit the performance).

Commits
-------

a46270a Don't use reflections when possible

Author: fabpot

Container.php

@@ -363,9 +363,8 @@ public function initialized($id)
     public function getServiceIds()
     {
         $ids = array();
-        $r = new \ReflectionClass($this);
-        foreach ($r->getMethods() as $method) {
-            if (preg_match('/^get(.+)Service$/', $method->name, $match)) {
+        foreach (get_class_methods($this) as $method) {
+            if (preg_match('/^get(.+)Service$/', $method, $match)) {
                 $ids[] = self::underscore($match[1]);
             }
         }