Upgrade clang-tidy on CI. (#5469)

* Correct all clang-tidy errors.
* Upgrade clang-tidy to 10 on CI.

Co-authored-by: Hyunsu Cho <chohyu01@cs.washington.edu>

tests/cpp/data/test_device_adapter.cu

@@ -50,6 +50,6 @@ void TestCudfAdapter()
   });
 }
 
-TEST(device_adapter, CudfAdapter) {
+TEST(DeviceAdapter, CudfAdapter) {
   TestCudfAdapter();
 }