Put back initialization of properties in trainer

[daniellepintz]

What does this PR do?

• Fix breaking change introduced in Deprecate TrainerProperties Mixin and move property definitions directly into trainer.py #9495 and pointed out by @carmocca. Put back properties that should have been initialized in trainer
• Put back line in a test that tests init of these properties
• Deleted properties.py - apparently there was a bad merge from master in Deprecate TrainerProperties Mixin and move property definitions directly into trainer.py #9495 that caused this file to not be deleted

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[codecov]

Codecov Report

Merging #9594 (130eae8) into master (c66d30a) will decrease coverage by 3%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #9594    +/-   ##
=======================================
- Coverage      92%     89%    -3%     
=======================================
  Files         181     180     -1     
  Lines       15728   15305   -423     
=======================================
- Hits        14446   13586   -860     
- Misses       1282    1719   +437