virtcontainers: Add context when creating tests sandboxes

We can use the background context when creating test sandboxes from the
sanbox unit tests. This shuts the "trace called before context set"
erros down.

Fixes: #1048

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

virtcontainers/sandbox_test.go

@@ -1184,6 +1184,7 @@ func TestSandboxAttachDevicesVFIO(t *testing.T) {
 		storage:    &filesystem{},
 		hypervisor: &mockHypervisor{},
 		devManager: dm,
+		ctx:        context.Background(),
 	}
 
 	containers[c.id].sandbox = &sandbox
@@ -1565,6 +1566,7 @@ func TestAttachBlockDevice(t *testing.T) {
 		storage:    fs,
 		hypervisor: hypervisor,
 		config:     sconfig,
+		ctx:        context.Background(),
 	}
 
 	contID := "100"
@@ -1653,6 +1655,7 @@ func TestPreAddDevice(t *testing.T) {
 		hypervisor: hypervisor,
 		config:     sconfig,
 		devManager: dm,
+		ctx:        context.Background(),
 	}
 
 	contID := "100"
@@ -1743,6 +1746,7 @@ func TestStartNetworkMonitor(t *testing.T) {
 		networkNS: NetworkNamespace{
 			NetNsPath: fmt.Sprintf("/proc/%d/task/%d/ns/net", os.Getpid(), unix.Gettid()),
 		},
+		ctx: context.Background(),
 	}
 
 	err = s.startNetworkMonitor()