bug symfony#59136 [DependencyInjection] Reset env vars with kernel.reset (faizanakram99)

This PR was merged into the 7.1 branch.

Discussion
----------

[DependencyInjection] Reset env vars with `kernel.reset`

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Issues        | Fix symfony#59128
| License       | MIT

As mentioned in symfony#59128 and symfony#54666 (comment) (and proceeding comments), EnvVarProcessor isn't tagged with kernel.reset, hence its reset method is never called in ServicesResetter.

Another issue was that env vars are cached high up in stack (in Container class) and even if EnvVarProcessor's cached env vars are cleared, env var loaders still won't be called as env var loaders are called only for missing env keys.

This PR fixes symfony#59128 by adding the missing tag and also clears "env cache" of Container in `EnvVarProcessor::reset()` method (i.e. whenever env vars of EnvVarProcessor are cleared). This is a safe change and won't break existing apps using symfony messenger.

cc `@bendavies`

Commits
-------

4c9e1a4 fix(dependency-injection): reset env vars with kernel.reset

Author: fabpot

src/Symfony/Bundle/FrameworkBundle/Resources/config/services.php

@@ -195,6 +195,7 @@ class_exists(WorkflowEvents::class) ? WorkflowEvents::ALIASES : []
                 tagged_iterator('container.env_var_loader'),
             ])
             ->tag('container.env_var_processor')
+            ->tag('kernel.reset', ['method' => 'reset'])
 
         ->set('slugger', AsciiSlugger::class)
             ->args([

src/Symfony/Component/DependencyInjection/Container.php

@@ -290,6 +290,14 @@ public function reset(): void
         $this->envCache = $this->services = $this->factories = $this->privates = [];
     }
 
+    /**
+     * @internal
+     */
+    public function resetEnvCache(): void
+    {
+        $this->envCache = [];
+    }
+
     /**
      * Gets all service ids.
      *

src/Symfony/Component/DependencyInjection/EnvVarProcessor.php

@@ -374,5 +374,9 @@ public function reset(): void
     {
         $this->loadedVars = [];
         $this->loaders = $this->originalLoaders;
+
+        if ($this->container instanceof Container) {
+            $this->container->resetEnvCache();
+        }
     }
 }