Regression benchmark

[GT9505]

This PR fixed several bugs to run MMTracking correctly.
It also changed the evaluation hook in siamese rpn config.

[codecov]

Codecov Report

Merging #219 (3271f40) into master (b3eedb1) will decrease coverage by 0.54%.
The diff coverage is 65.38%.

❗ Current head 3271f40 differs from pull request most recent head da4568b. Consider uploading reports for the commit da4568b to get more accurate results

@@            Coverage Diff             @@
##           master     #219      +/-   ##
==========================================
- Coverage   69.96%   69.42%   -0.55%     
==========================================
  Files          87       87              
  Lines        4402     4415      +13     
  Branches      863      867       +4     
==========================================
- Hits         3080     3065      -15     
- Misses       1037     1059      +22     
- Partials      285      291       +6     

Flag	Coverage Δ
unittests	69.39% <65.38%> (-0.48%)	⬇️

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Impacted Files	Coverage Δ
mmtrack/core/evaluation/eval_hooks.py	65.00% <64.00%> (-11.93%)	⬇️
mmtrack/apis/train.py	16.66% <100.00%> (+2.12%)	⬆️
mmtrack/models/mot/trackers/tracktor_tracker.py	63.09% <0.00%> (-15.48%)	⬇️
mmtrack/datasets/pipelines/transforms.py	85.31% <0.00%> (-2.82%)	⬇️

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