Misc. refactoring and fixes

[AdeelH]

Overview

This PR makes a few minor changes. See commits for details.

Checklist

• Added needs-backport label if PR is bug fix that applies to previous minor release
• Ran scripts/format_code and committed any changes
• Documentation updated if needed
• PR has a name that won't get you publicly shamed for vagueness

Notes

N/A

Testing Instructions

• See updated unit tests.

[codecov]

Codecov Report

Merging #1838 (f4c7952) into master (3ce9186) will increase coverage by 0.15%.
The diff coverage is 97.88%.

@@            Coverage Diff             @@
##           master    #1838      +/-   ##
==========================================
+ Coverage   79.88%   80.03%   +0.15%     
==========================================
  Files         188      188              
  Lines        9182     9236      +54     
==========================================
+ Hits         7335     7392      +57     
+ Misses       1847     1844       -3     

Impacted Files	Coverage Δ
.../core/data/raster_transformer/stats_transformer.py	85.41% <93.33%> (+8.27%)	⬆️
...ervision_core/rastervision/core/data/utils/misc.py	83.47% <94.44%> (+1.91%)	⬆️
...astervision_core/rastervision/core/raster_stats.py	99.10% <99.00%> (+0.35%)	⬆️
rastervision_core/rastervision/core/box.py	100.00% <100.00%> (ø)
...n/core/data/raster_transformer/cast_transformer.py	100.00% <100.00%> (ø)
...ision/core/evaluation/classification_evaluation.py	96.87% <100.00%> (+4.28%)	⬆️
...stervision_pipeline/rastervision/pipeline/utils.py	80.00% <100.00%> (+8.57%)	⬆️

... and 1 file with indirect coverage changes