Remove refresh_from_db calls from graphs/views.py

[joseph-sentry]

Purpose/Motivation

same issue as before, django uses the primary key to refresh from the db which leads to this query being run:

SELECT branches.branch, branches.repoid, branches.authors, branches.head,
       branches.base, branches.updatestamp
FROM branches
WHERE branches.branch = %s
LIMIT 21

Links to relevant tickets

Sentry issue

What does this PR do?

• remove refresh_from_db calls

[sentry-io]

🔍 Existing Issues For Review

Your pull request is modifying functions with the following pre-existing issues:

📄 File: graphs/views.py

Function	Unhandled Issue
get_coverage	Branch.MultipleObjectsReturned: get() returned more than one Branch -- it returned more than 20! /{service}/{owner_usernam... Event Count: 145
get_commit	Branch.MultipleObjectsReturned: get() returned more than one Branch -- it returned more than 20! /{service}/{owner_username}... Event Count: 1

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[codecov-staging]

Codecov Report

All modified and coverable lines are covered by tests ✅

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[codecov-qa]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2270abf) 96.03% compared to head (d9377c0) 96.03%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #354      +/-   ##
==========================================
- Coverage   96.03%   96.03%   -0.01%     
==========================================
  Files         626      626              
  Lines       16233    16231       -2     
==========================================
- Hits        15590    15588       -2     
  Misses        643      643              

Flag	Coverage Δ
unit	96.03% <100.00%> (-0.01%)	⬇️
unit-latest-uploader	96.03% <100.00%> (-0.01%)	⬇️

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[codecov-public-qa]

Codecov Report

Merging #354 (d9377c0) into main (2270abf) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #354      +/-   ##
==========================================
- Coverage   96.03%   96.03%   -0.01%     
==========================================
  Files         626      626              
  Lines       16233    16231       -2     
==========================================
- Hits        15590    15588       -2     
  Misses        643      643              

Flag	Coverage Δ
unit	96.03% <100.00%> (-0.01%)	⬇️
unit-latest-uploader	96.03% <100.00%> (-0.01%)	⬇️

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

Files	Coverage Δ
graphs/views.py	93.00% <100.00%> (-0.10%)	⬇️