performant latest proxy_configs SQL query

[akostadinov]

wanted to make #2921 use code and not direct SQL but failed. I found a simpler way to replace the existing scope though that seems also fast. I have not done proper performance comparison. I just thought having it as a scope has it's benefits.

btw this is related to rzane/baby_squeel#123, hopefully we can avoid direct SQL usage at some point

[codecov]

Codecov Report

Merging #2951 (02a058c) into master (007f830) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2951      +/-   ##
==========================================
+ Coverage   93.30%   93.34%   +0.03%     
==========================================
  Files        2774     2775       +1     
  Lines       89456    89806     +350     
==========================================
+ Hits        83468    83830     +362     
+ Misses       5988     5976      -12     

Impacted Files	Coverage Δ
app/models/proxy_config.rb	96.51% <100.00%> (-0.12%)	⬇️
app/lib/three_scale/api/responder.rb	95.83% <0.00%> (-2.09%)	⬇️
app/models/application_record.rb	88.88% <0.00%> (ø)
test/unit/helpers/messages_helper_test.rb
...ntegration/finance/api/invoices_controller_test.rb	100.00% <0.00%> (ø)
...on/user-management-api/buyers_applications_test.rb	100.00% <0.00%> (ø)
app/lib/api_authentication/by_access_token.rb	97.45% <0.00%> (+0.84%)	⬆️
lib/tasks/impersonation_admin_user.rake	100.00% <0.00%> (+10.00%)	⬆️
lib/tasks/multitenant/tenants.rake	67.92% <0.00%> (+20.75%)	⬆️

---

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 007f830...02a058c. Read the comment docs.

[josemigallas]

Added to #2921
Kudos! 🥇