[cherry-pick] Cache image list with digest key

[stonezdj]

fixes #19429

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Comprehensive Summary of your change

Issue being fixed

Fixes #(issue)

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• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
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• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[wy65701436]

lgtm

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (4f19f84) 67.55% compared to head (1e1b9ca) 67.52%.
Report is 6 commits behind head on release-2.10.0.

Additional details and impacted files

@@                Coverage Diff                 @@
##           release-2.10.0   #19838      +/-   ##
==================================================
- Coverage           67.55%   67.52%   -0.03%     
==================================================
  Files                 991      991              
  Lines              109175   109181       +6     
  Branches             2719     2719              
==================================================
- Hits                73748    73728      -20     
- Misses              31458    31485      +27     
+ Partials             3969     3968       -1     

Flag	Coverage Δ
unittests	67.52% <33.33%> (-0.03%)	⬇️

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

Files	Coverage Δ
src/controller/proxy/controller.go	15.59% <50.00%> (-0.26%)	⬇️
src/controller/proxy/manifestcache.go	26.27% <0.00%> (-0.59%)	⬇️

... and 6 files with indirect coverage changes