[Fix] Remove confusing img_scales in pipelines

[gaotongxiao]

Fix #888

[codecov]

Codecov Report

Merging #1007 (672f1f0) into main (0329ff9) will decrease coverage by 0.14%.
The diff coverage is n/a.

❗ Current head 672f1f0 differs from pull request most recent head 8398ff3. Consider uploading reports for the commit 8398ff3 to get more accurate results

@@            Coverage Diff             @@
##             main    #1007      +/-   ##
==========================================
- Coverage   83.77%   83.62%   -0.15%     
==========================================
  Files         170      170              
  Lines       11374    11374              
  Branches     1750     1750              
==========================================
- Hits         9528     9512      -16     
- Misses       1468     1484      +16     
  Partials      378      378              

Flag	Coverage Δ
unittests	83.62% <ø> (-0.15%)	⬇️

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

Impacted Files	Coverage Δ
mmocr/datasets/pipelines/transforms.py	81.45% <0.00%> (-2.54%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9cfa29f...8398ff3. Read the comment docs.