cleanup: resolve parallel test issue

This commit resolves parallel test issues
and also excludes internal/util/conn_pool_test.go
as those test can't run in parallel.

Updates: #1586

Signed-off-by: Yati Padia <ypadia@redhat.com>

internal/rbd/controllerserver_test.go

@@ -23,6 +23,7 @@ import (
 )
 
 func TestIsThickProvisionRequest(t *testing.T) {
+	t.Parallel()
 	req := &csi.CreateVolumeRequest{
 		Name: "fake",
 		Parameters: map[string]string{