testing: fix resource warning with ManagedHTTPServer

We fork a subprocess to serve requests, but the listening socket is bound
in server constructor and inherited by subprocess. With this pattern, we
have to explicitly close the socket from parent process to prevent the
leak.
5 jobs for fix/testing-resourcewarnings in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

04:37:29

running SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

27371:36:49

failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-WIP

05:13:02

failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

05:57:16

failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

08:08:37