DM-40121 Optimizations in QuantumGraph loading

[natelust]

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

Patch coverage: 75.00% and no project coverage change.

Comparison is base (0787220) 87.79% compared to head (0ab0ed0) 87.80%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #870   +/-   ##
=======================================
  Coverage   87.79%   87.80%           
=======================================
  Files         274      274           
  Lines       36005    36003    -2     
  Branches     7535     7533    -2     
=======================================
+ Hits        31612    31613    +1     
+ Misses       3227     3225    -2     
+ Partials     1166     1165    -1     

Files Changed	Coverage Δ
python/lsst/daf/butler/core/quantum.py	86.89% <50.00%> (-0.55%)	⬇️
python/lsst/daf/butler/core/dimensions/_records.py	83.64% <100.00%> (-0.11%)	⬇️
python/lsst/daf/butler/core/persistenceContext.py	59.25% <100.00%> (ø)

... and 1 file with indirect coverage changes

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