Encode dir obj names before expiration (#19305)

Object names of directory objects qualified for ExpiredObjectAllVersions
must be encoded appropriately before calling on deletePrefix on their
erasure set.

e.g., a directory object and regular objects with overlapping prefixes
could lead to the expiration of regular objects, which is not the 
intention of ILM. 

```
bucket/dir/ ---> directory object
bucket/dir/obj-1
```

When `bucket/dir/` qualifies for expiration, the current implementation would
remove regular objects under the prefix `bucket/dir/`, in this case,
`bucket/dir/obj-1`.

internal/event/name_test.go

@@ -36,7 +36,7 @@ func TestNameExpand(t *testing.T) {
 			ObjectCreatedCompleteMultipartUpload, ObjectCreatedCopy, ObjectCreatedPost, ObjectCreatedPut,
 			ObjectCreatedPutRetention, ObjectCreatedPutLegalHold, ObjectCreatedPutTagging, ObjectCreatedDeleteTagging,
 		}},
-		{ObjectRemovedAll, []Name{ObjectRemovedDelete, ObjectRemovedDeleteMarkerCreated, ObjectRemovedNoOP}},
+		{ObjectRemovedAll, []Name{ObjectRemovedDelete, ObjectRemovedDeleteMarkerCreated, ObjectRemovedNoOP, ObjectRemovedDeleteAllVersions}},
 		{ObjectAccessedHead, []Name{ObjectAccessedHead}},
 	}