`check.py` still calls coord.bounds() instead of coord.core_bounds() in some cases
**Describe the bug**
In #1912 , the cmor checker calls to the coordinates was made to use the array module specific to the coordinate, instead of automatically converting everything to numpy arrays.

There is still one case in which the coordinate bounds for an aux coord (3D array) may get realised:

https://github.com/ESMValGroup/ESMValCore/blob/f00b6c6190a114ffe12aea007bd31b066d2cb8d9/esmvalcore/cmor/check.py#L776

It would be good to change that case for it to call coord.core_bounds()
diff --git a/esmvalcore/cmor/check.py b/esmvalcore/cmor/check.py
index 29f0f74e7..4eb057730 100644
--- a/esmvalcore/cmor/check.py
+++ b/esmvalcore/cmor/check.py
@@ -773,8 +773,8 @@ class CMORCheck():
             else:
                 new_lons = coord.core_points().copy()
                 new_lons = self._set_range_in_0_360(new_lons)
-                if coord.bounds is not None:
-                    new_bounds = coord.bounds.copy()
+                if coord.core_bounds() is not None:
+                    new_bounds = coord.core_bounds().copy()
                     new_bounds = self._set_range_in_0_360(new_bounds)
                 else:
                     new_bounds = None
['esmvalcore/cmor/check.py']