DM-53370: Free butler resources after use

[timj]

Requires lsst/daf_butler#1291 and lsst/pipe_base#531

Checklist

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

[codecov]

Codecov Report

❌ Patch coverage is 76.53061% with 46 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.10%. Comparing base (24947d5) to head (a55c6b0).
⚠️ Report is 6 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
python/lsst/ctrl/mpexec/cli/script/qgraph.py	54.34%	13 Missing and 8 partials ⚠️
python/lsst/ctrl/mpexec/cli/script/run.py	51.42%	10 Missing and 7 partials ⚠️
python/lsst/ctrl/mpexec/cli/script/report.py	89.65%	1 Missing and 2 partials ⚠️
python/lsst/ctrl/mpexec/cli/script/build.py	50.00%	1 Missing and 1 partial ⚠️
python/lsst/ctrl/mpexec/cli/script/cleanup.py	89.47%	1 Missing and 1 partial ⚠️
python/lsst/ctrl/mpexec/singleQuantumExecutor.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #357      +/-   ##
==========================================
+ Coverage   85.95%   86.10%   +0.14%     
==========================================
  Files          44       44              
  Lines        2542     2554      +12     
  Branches      264      265       +1     
==========================================
+ Hits         2185     2199      +14     
+ Misses        256      253       -3     
- Partials      101      102       +1     

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