Fix Last Pull time on parent/child artifacts and on creation

[BojanZelic]

Thank you for contributing to Harbor!

Comprehensive Summary of your change

Does 2 things:

• when creating a artifact through the pull through cache, because all creations are the result of pulls, sets the last pull time automatically
• if a child artifact is pulled, then updates the parent and also sets the last_pull time to be the same as what it was set to on the child.

Issue being fixed

Fixes #22390

Please indicate you've done the following:

• 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"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• 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.

[BojanZelic]

I wasn't able to run this specific test due to some dependencies on postgres, so not 100% sure if this test will pass.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46.67%. Comparing base (c8c11b4) to head (a6f2fe8).
⚠️ Report is 572 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #22402      +/-   ##
==========================================
+ Coverage   45.36%   46.67%   +1.30%     
==========================================
  Files         244      252       +8     
  Lines       13333    14255     +922     
  Branches     2719     2927     +208     
==========================================
+ Hits         6049     6653     +604     
- Misses       6983     7246     +263     
- Partials      301      356      +55     

Flag	Coverage Δ
unittests	46.67% <ø> (+1.30%)	⬆️

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