minor #14470 [Security] Remove extra argument from call to EntityManager#flush() (chalasr)

This PR was merged into the 4.4 branch.

Discussion
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[Security] Remove extra argument from call to EntityManager#flush()

See https://github.com/doctrine/orm/blob/master/UPGRADE.md#bc-break-removed-entitymanagerflushentity-and-entitymanagerflushentities

Commits
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3194c22 [Security] Remove extra argument from call to EntityManager#flush()

Author: javiereguiluz

security/password_migration.rst

@@ -190,7 +190,7 @@ storing the newly created password hash::
             $user->setPassword($newEncodedPassword);
 
             // execute the queries on the database
-            $this->getEntityManager()->flush($user);
+            $this->getEntityManager()->flush();
         }
     }