Deprecate TrainerProperties Mixin and move property definitions directly into trainer.py

[daniellepintz]

What does this PR do?

Fixes #8946

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[codecov]

Codecov Report

Merging #9495 (e1417c8) into master (86c0335) will decrease coverage by 5%.
The diff coverage is 94%.

❗ Current head e1417c8 differs from pull request most recent head 238eb1c. Consider uploading reports for the commit 238eb1c to get more accurate results

@@           Coverage Diff           @@
##           master   #9495    +/-   ##
=======================================
- Coverage      93%     88%    -5%     
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  Files         180     180            
  Lines       15090   15469   +379     
=======================================
- Hits        14019   13604   -415     
- Misses       1071    1865   +794     

[ananthsub]

Thanks @daniellepintz !

We should do the same thing for this mixin too: https://github.com/PyTorchLightning/pytorch-lightning/blob/master/pytorch_lightning/trainer/deprecated_api.py

This can be in a separate PR

[tchaton]

Not a huge fan, but I guess it is the first step toward something better.

[daniellepintz]

@carmocca made the fix in #9594. Should I copy all the properties here or just the ones that are intialized?

https://github.com/PyTorchLightning/pytorch-lightning/blob/938a191406fff5f51fba03fcf824f22d8d23c2e0/pytorch_lightning/trainer/properties.py#L55-L76