Tied weights load
# What does this PR do?

This continue cleaning up a bit the model loading by:
1. Using the new `_tied_weight_keys` class variable when deleting weights without warning for safetensors serialization
2. Fix the logic that deletes tied params in missing keys and add a test (which fails on main)
3. As discussed internally, use a logger.info for the unexepected keys warning when the class used to load the model does not match the class in the config.
_The documentation is not available anymore as the PR was closed or merged._