fix: transpose scale_factors to match the shape of [batch_size, 4]

[Raysilience]

Motivation

When using mmdet.apis.inference.inference_detector to infer a batch of images, I ran into the problem at the 258th line of test_mixins.py indicating the shape mismatch between det_bboxes and 'scale_factors. It turns out that a float scale factor will be expanded by 4 at line 241, thus, outputting a vector of shape (4, batch_size). Whereas det_bboxes` has a shape of [batch_size, 5]

Modification

Transpose scale_factors to match the shape of [batch_size, 4]

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repos?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit test to ensure the correctness.
3. If the modification has potential influence on downstream projects, this PR should be tested with downstream projects, like MMDet or MMCls.
4. The documentation has been modified accordingly, like docstring or example tutorials.

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[ZwwWayne]

Hi @Raysilience

Thanks for your kind PR. It seems that CLA is not signed. Could you sign the CLA so that eventually we could merge this PR after review? You can check the contents and follow the instruction in the communication box shown as below

[Raysilience]

Hi @ZwwWayne ,
I've just signed it. Now you should be able to merge.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (f8bbba2) 64.08% compared to head (c183168) 64.00%.
Report is 94 commits behind head on dev.

Files	Patch %	Lines
mmdet/models/roi_heads/test_mixins.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev    #8757      +/-   ##
==========================================
- Coverage   64.08%   64.00%   -0.09%     
==========================================
  Files         361      361              
  Lines       29525    29525              
  Branches     5020     4918     -102     
==========================================
- Hits        18922    18897      -25     
- Misses       9589     9611      +22     
- Partials     1014     1017       +3     

Flag	Coverage Δ
unittests	64.00% <0.00%> (-0.09%)	⬇️

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