Remove deprecated datamodule lifecycle properties

[mayeroa]

What does this PR do?

Part of #10312

Does your PR introduce any breaking changes? If yes, please list them.

They are deprecated

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[ananthsub]

Thanks for working on this @mayeroa !
With this change, we should also remove the following:

• https://github.com/PyTorchLightning/pytorch-lightning/blob/ce3e63262a7247c1111375b28c90bdd83b42bf3f/pytorch_lightning/core/datamodule.py#L94-L105
• https://github.com/PyTorchLightning/pytorch-lightning/blob/ce3e63262a7247c1111375b28c90bdd83b42bf3f/pytorch_lightning/core/datamodule.py#L409-L483
• Any references to these properties in the trainer, like here: https://github.com/PyTorchLightning/pytorch-lightning/blob/ce3e63262a7247c1111375b28c90bdd83b42bf3f/pytorch_lightning/trainer/connectors/data_connector.py#L143

[mayeroa]

Should be better now :)

[carmocca]

Big one!