Revert "e2e/container: Skip umask test until engine support"

This reverts commit 45a3e0b.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

e2e/container/run_test.go

@@ -112,7 +112,6 @@ func TestRunWithCgroupNamespace(t *testing.T) {
 
 func TestRunUmask(t *testing.T) {
 	environment.SkipIfDaemonNotLinux(t)
-	t.Skip("FIXME: un-skip once e2e tests v29.8.0")
 
 	testCases := []struct {
 		name     string