[Enhance]: Update rpn upgrade scripts for v2.5.0 compatibility

[ZwwWayne]

No description provided.

[hellock]

Task linked: CU-4huc17 RPN model upgrade (for #3221)

[codecov]

Codecov Report

Merging #3986 into master will increase coverage by 0.01%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3986      +/-   ##
==========================================
+ Coverage   62.25%   62.26%   +0.01%     
==========================================
  Files         221      221              
  Lines       16314    16314              
  Branches     2759     2759              
==========================================
+ Hits        10156    10158       +2     
+ Misses       5666     5663       -3     
- Partials      492      493       +1     

Flag	Coverage Δ
#unittests	62.26% <0.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
mmdet/models/dense_heads/rpn_head.py	84.93% <0.00%> (ø)
mmdet/models/detectors/cornernet.py	94.87% <0.00%> (-5.13%)	⬇️
mmdet/models/dense_heads/corner_head.py	74.86% <0.00%> (-1.92%)	⬇️
mmdet/models/roi_heads/test_mixins.py	59.82% <0.00%> (+9.40%)	⬆️

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