feature #23936 Remove some sf2 references (fabpot)

This PR was merged into the 3.4 branch.

Discussion
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Remove some sf2 references

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Those `sf2` references can be safely remove and changed to `symfony` as there are internal or they don't break anything when upgrading Symfony's version:

* Flashes are ephemeral, so changing the key in the session is not a problem;
* Changing the local storage key for the profiler is not an issue as this is a dev tool.

Commits
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1b0265417b removed sf2 references

Author: fabpot

Loader/XmlFileLoader.php

@@ -597,7 +597,7 @@ public function validateSchema(\DOMDocument $dom)
         foreach ($schemaLocations as $namespace => $location) {
             $parts = explode('/', $location);
             if (0 === stripos($location, 'phar://')) {
-                $tmpfile = tempnam(sys_get_temp_dir(), 'sf2');
+                $tmpfile = tempnam(sys_get_temp_dir(), 'symfony');
                 if ($tmpfile) {
                     copy($location, $tmpfile);
                     $tmpfiles[] = $tmpfile;