Improve notices endpoint

[samhotep]

Done

Querying notices takes quite a while to complete, ~15s on average. This PR hopes to improve the db query by reworking how the notice json is built.

QA

• Check out this feature branch
• Run the site using the command ./run serve
• View the site locally in your web browser at: http://0.0.0.0:8030/
• Open /security/cves.json and /security/notices.json
• Check that they both return in reasonable time

Notes

• You'll need a database with a significant number of records to replicate the issue (~9000 notices, ~240000 cves)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.85%. Comparing base (55311e3) to head (0fd7100).
Report is 10 commits behind head on main.

❗ Current head 0fd7100 differs from pull request most recent head 6b7c018

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #146      +/-   ##
==========================================
+ Coverage   85.00%   85.85%   +0.85%     
==========================================
  Files          29       29              
  Lines        1480     1570      +90     
==========================================
+ Hits         1258     1348      +90     
  Misses        222      222              

Flag	Coverage Δ
python	85.85% <ø> (+0.85%)	⬆️

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[hloeung]

FWIW, there's been a few timeout related issues in the past, some of it being resolved by reducing the query limit. Hopefully this fixes the DB query itself and for good. Here are some:

#129
#101
#59
#31
#20

I'm not sure if we can improve cacheability of these requests as well. This would reduce the backend load and have the fronting content-cache units service requests from their local cache.

[sudhackar]

I suppose this is causing canonical/ubuntu.com#13956