Fix progress bar print error when called before training

[ryanking13]

What does this PR do?

Fixes #7673

• Check progress bar existence before printing
• Use predict_progress_bar when printing at predict_step

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[codecov]

Codecov Report

Merging #7674 (75c7d93) into master (0c958c5) will decrease coverage by 5%.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master   #7674    +/-   ##
=======================================
- Coverage      93%     88%    -5%     
=======================================
  Files         200     200            
  Lines       12955   12964     +9     
=======================================
- Hits        11991   11381   -610     
- Misses        964    1583   +619     

[ethanwharris]

Awesome, LGTM 😃

[Borda]

Pls update changelog

[ryanking13]

updated changelog