added support for test environment out of the box for server:run

                      
|Q            |A     |
|---          |---   |
|Bug Fix?     |no    |
|New Feature? |no    |
|BC Breaks?   |no    |
|Deprecations?|no    |
|Tests Pass?  |yes   |
|Fixed Tickets|#10461|
|License      |MIT   |
|Doc PR       |#3688 |
                      
This is assuming there is an app_test.php in the distro but since testing should be a best practice then it should be fine.