Fix channel_dim bug in TiffFileWSIReader and CuCIMWSIReader (#6514)

Fixes #6511 .

### Description

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

---------

Signed-off-by: KumoLiu <yunl@nvidia.com>

Author: KumoLiu

monai/data/wsi_reader.py

@@ -824,7 +824,7 @@ def _get_patch(
                     f"The image is expected to have three or four color channels in '{mode}' mode but has "
                     f"{patch.shape[self.channel_dim]}. "
                 )
-            patch = patch[:3]
+            patch = np.take(patch, [0, 1, 2], self.channel_dim)
 
         return patch
 
@@ -1183,6 +1183,6 @@ def _get_patch(
                     f"The image is expected to have three or four color channels in '{mode}' mode but has "
                     f"{patch.shape[self.channel_dim]}. "
                 )
-            patch = patch[:3]
+            patch = np.take(patch, [0, 1, 2], self.channel_dim)
 
         return patch

tests/test_wsireader.py

@@ -81,15 +81,27 @@
 TEST_CASE_3 = [
     WSI_GENERIC_TIFF_PATH,
     {"channel_dim": -1},
-    {"location": (WSI_GENERIC_TIFF_HEIGHT // 2, WSI_GENERIC_TIFF_WIDTH // 2), "size": (2, 1), "level": 0},
-    np.moveaxis(np.array([[[246], [246]], [[246], [246]], [[246], [246]]], dtype=np.uint8), 0, -1),
+    {"location": (WSI_GENERIC_TIFF_HEIGHT // 2, WSI_GENERIC_TIFF_WIDTH // 2), "size": (4, 1), "level": 0},
+    np.moveaxis(
+        np.array(
+            [[[246], [246], [246], [246]], [[246], [246], [246], [246]], [[246], [246], [246], [246]]], dtype=np.uint8
+        ),
+        0,
+        -1,
+    ),
 ]
 
 TEST_CASE_4 = [
     WSI_GENERIC_TIFF_PATH,
     {"channel_dim": 2},
-    {"location": (0, 0), "size": (2, 1), "level": 8},
-    np.moveaxis(np.array([[[242], [242]], [[242], [242]], [[242], [242]]], dtype=np.uint8), 0, -1),
+    {"location": (0, 0), "size": (4, 1), "level": 8},
+    np.moveaxis(
+        np.array(
+            [[[242], [242], [242], [242]], [[242], [242], [242], [242]], [[242], [242], [242], [242]]], dtype=np.uint8
+        ),
+        0,
+        -1,
+    ),
 ]
 
 TEST_CASE_5 = [