SCA: dropped import duplicates, fixed a few cases of php core API misuse (#5639)

* SCA: dropped import duplicates, fixed a few cases of php core API misuse

* SCA: partial revert to probe if semaphore build gets fixed

Author: kalessil

tests/unit/Codeception/Module/RestTest.php

@@ -1,7 +1,7 @@
 <?php
 
 use Codeception\Test\Unit;
-use Codeception\Util\Stub as Stub;
+use Codeception\Util\Stub;
 
 /**
  * Class RestTest