Update all the examples & notebooks to use new APIs (14/July)

**Describe the bug**
As we unified metrics APIs, @yiheng-wang-nv will simplify all the tutorials and examples to use the latest APIs when `decollate batch` feature is also merged.
Pending on this PR: https://github.com/Project-MONAI/MONAI/pull/2315