Remove deprecated mode argument from ModelSummary

[kaushikb11]

What does this PR do?

Part of #10312

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[carmocca]

Hey @kaushikb11, I had #10446 already opened. Do you mind merging that and then fully removing the argument here?

[codecov]

Codecov Report

Merging #10449 (87e0f73) into master (fa0ed17) will decrease coverage by 4%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master   #10449    +/-   ##
========================================
- Coverage      92%      89%    -4%     
========================================
  Files         179      179            
  Lines       16288    16273    -15     
========================================
- Hits        15060    14418   -642     
- Misses       1228     1855   +627