Fix LightningCLI loading of hyperparameters from ckpt_path failing for subclass model mode

[mauvilsa]

What does this PR do?

Fixes torchgeo/torchgeo#2995
Maybe also fixes mehta-lab/VisCy#291

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📚 Documentation preview 📚: https://pytorch-lightning--21246.org.readthedocs.build/en/21246/

[adamjstewart]

Looks like this didn't make it into 2.5.6. Will there be a 2.5.7 or will 2.6.0 be next?

[deependujha]

Hi @adamjstewart, We will probably do 2.6.0 early next week.