Fix sporadic failures of AttachContainerCmdIT tests (#1483)

* Remove unnecessary semicolons

* Make log field of AttachContainerTestCallback final

* Reformat AttachContainerCmdIT.java

* Fix sporadic failures of AttachContainerCmdIT tests

* Remove no longer required "sleep 1" before reading line and echoing it in "attachContainerWithStdin" test

* Remove no longer required cyclic output to stdout and stderr in "attachContainerWithTTY" test

Co-authored-by: Alexander Koshevoy <Alexander.Koshevoy@jetbrains.com>