Refactor trainer._log_device_info() method and warnings

Proposed refactor

Raised in discussion by @ananthsub and @justusschock in #11001 1/n Generalize internal checks for Accelerator in Trainer - remove trainer._device_type

Motivation

_log_device_info() in trainer is too verbose and message are not helpful
https://github.com/PyTorchLightning/pytorch-lightning/blob/master/pytorch_lightning/trainer/trainer.py#L1630-L1661

Accelerator/device selection Only happens in accelerator_connector, and related warning and logging should happen in accelerator_connector as well.

The warning and logic can be merged into select_accelerator_type()

Pitch

Simplify the log warning in trainer._log_device_info() and make it less verbose, remove unnecessary warnings, reduce log level from warning to debug

Move _log_device_info() to accelerator_connector and call at the end of the init(), or merge the logic into accelerator_connector

Additional context

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cc @justusschock @awaelchli @akihironitta @carmocca @edward-io @ananthsub @kaushikb11 @ninginthecloud