tests/int: rework/simplify setup and teardown

1. Get rid of fixed ROOT, *_BUNDLE, and CONSOLE_SOCKET dirs.
   Now they are temporary directories created in setup_bundle.

2. Automate containers cleanup: instead of having to specify all
   containers to be removed, list and destroy everything (which is
   now possible since every test case has its own unique root).

3. Randomize cgroup paths so two tests running in parallel won't
   use the same cgroup.

Now it's theoretically possible to execute tests in parallel.
Practically it's not possible yet because bats uses GNU parallel,
which do not provide a terminal for whatever it executes, and
many runc tests (all those that run containers with terminal:
true) needs a tty. This may possibly be addressed later.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/list.bats

@@ -3,20 +3,16 @@
 load helpers
 
 function setup() {
-	unset ALT_ROOT
-	teardown
 	setup_busybox
-	ALT_ROOT=$(mktemp -d "$BATS_RUN_TMPDIR/runc-2.XXXXXX")
+	ALT_ROOT="$ROOT/alt"
+	mkdir -p "$ALT_ROOT/state"
 }
 
 function teardown() {
 	if [ -n "$ALT_ROOT" ]; then
-		ROOT="$ALT_ROOT" teardown_running_container test_box1
-		ROOT="$ALT_ROOT" teardown_running_container test_box2
-		ROOT="$ALT_ROOT" teardown_running_container test_box3
-		rm -rf "$ALT_ROOT"
+		ROOT="$ALT_ROOT" teardown_bundle
 	fi
-	teardown_busybox
+	teardown_bundle
 }
 
 @test "list" {