Update test for ckpt+val_check_interval

[rohitgr7]

What does this PR do?

While reviewing #7032, noticed that this test is a bit incorrect since with total train batches=12 and val_check_interval=0.33, actual batch interval = 4 which aligns with the train_loop perfectly. In the test, we need to check for the case where val_check_interval doesn't align train batches, so updated the test here.

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[tchaton]

Good catch !

[codecov]

Codecov Report

Merging #7084 (dbe0f78) into master (d12c6cf) will decrease coverage by 0%.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #7084   +/-   ##
======================================
- Coverage      92%     92%   -0%     
======================================
  Files         197     197           
  Lines       12634   12677   +43     
======================================
+ Hits        11649   11666   +17     
- Misses        985    1011   +26     

[Borda]

lgtm