Fix restoring training state during trainer.fit only

[rohitgr7]

What does this PR do?

Fixes #9404
TODO: need to merge/add similar tests for datamodule and callbacks in another PR.

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[codecov]

Codecov Report

Merging #9413 (dde4875) into master (3392215) will decrease coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #9413    +/-   ##
=======================================
- Coverage      93%     89%    -4%     
=======================================
  Files         177     178     +1     
  Lines       15527   15597    +70     
=======================================
- Hits        14386   13821   -565     
- Misses       1141    1776   +635     

[carmocca]

Code looks good, some comments on the tests