[Fix] Fix MixUp transform filter boxes failing case

[dvansa]

Motivation

When using MixUp pipeline transform with the filter boxes enabled (skip_filter=False) there is the following failing case: when all boxes are marked to be removed the filtering step is skiped and all boxes are kept (opposite behavior).

Modification

Removed the conditional statment causing the skip.
Extended MixUp unit test adding the case that was failing in the same fashion as RandomAffine test

Checklist

• Used Pre-commit or other linting tools are used to fix the potential lint issues.
• Added unit test. Verified correct behavior using pytest

[codecov]

Codecov Report

Merging #7080 (8fa40d0) into dev (4bdb312) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev    #7080      +/-   ##
==========================================
+ Coverage   62.41%   62.45%   +0.03%     
==========================================
  Files         330      330              
  Lines       26199    26198       -1     
  Branches     4436     4435       -1     
==========================================
+ Hits        16353    16361       +8     
+ Misses       8976     8967       -9     
  Partials      870      870              

Flag	Coverage Δ
unittests	62.43% <100.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
mmdet/datasets/pipelines/transforms.py	75.19% <100.00%> (+0.74%)	⬆️
mmdet/utils/misc.py	95.23% <0.00%> (-4.77%)	⬇️
mmdet/core/bbox/assigners/max_iou_assigner.py	72.36% <0.00%> (-1.32%)	⬇️
mmdet/core/bbox/samplers/random_sampler.py	80.55% <0.00%> (+5.55%)	⬆️

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[hhaAndroid]

@dvansa Thanks a lot for your contribution, please fix the lint.

[dvansa]

@hhaAndroid
The lint checks are failing due to some config README's missing the "<!-- [ALGORITHM] -->" flag which is out of scope for this PR.

Failed to find "<!-- [ALGORITHM] -->" flag from readme, please check configs/regnet/README.md again.
Failed to find "<!-- [ALGORITHM] -->" flag from readme, please check configs/resnest/README.md again.
Failed to find "<!-- [ALGORITHM] -->" flag from readme, please check configs/solo/README.md again.

After looking a bit further, it seems that the cause is an update on the pre-commit-hooks repository from 2 days ago.

[dvansa]

@hhaAndroid. Disregard my previous message. After rebasing with latest dev the lint problems are solved

[OpenMMLab-Assistant003]

Hi @dvansa！First of all, we want to express our gratitude for your significant PR in the MMDetection project. Your contribution is highly appreciated, and we are grateful for your efforts in helping improve this open-source project during your personal time. We believe that many developers will benefit from your PR.

We would also like to invite you to join our Special Interest Group (SIG) private channel on Discord, where you can share your experiences, ideas, and build connections with like-minded peers. To join the SIG channel, simply message moderator— OpenMMLab on Discord or briefly share your open-source contributions in the #introductions channel and we will assist you. Look forward to seeing you there! Join us ：https://discord.gg/UjgXkPWNqA

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Thank you again for your contribution❤ @dvansa