Increase time before exit in TestMultipleAttachRestart

Sometimes third attacher attaching to already stopped container.
Also I've changed prefix to attach and fixed cleanup on Fatal.
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Merge pull request #6415 from LK4D4/increase_timeout_in_test_attach

Increase time before exit in TestMultipleAttachRestart