Disable weight sharing for VarNet model (#5102)
Disable weight sharing for VarNet model (#5102)

Signed-off-by: mersad95zd <a7ab90d8b203bd248ec33bebdeb4b6c56b099409@gmail.com>

Fixes # .

### Description

Disable weight sharing in VarNet model.

### 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: mersad95zd <a7ab90d8b203bd248ec33bebdeb4b6c56b099409@gmail.com>
Project-MONAI/MONAI,Project-MONAI/MONAI,Project-MONAI/MONAI,Project-MONAI/MONAI