DM-41116: Few updates fiollowing Butler interface change

[andy-slac]

Butler is now an abstract class, and preferred way to instanciate butlers
is Butler.from_config. Execution butler requires a DirectButler instance,
updated the code to reflect that (somewhat hackish, but execution butler is
going to disappear any minute now or next year).

Checklist

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

[codecov]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (cb87889) 87.11% compared to head (9c6d022) 87.07%.

❗ Current head 9c6d022 differs from pull request most recent head 6f72300. Consider uploading reports for the commit 6f72300 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #268      +/-   ##
==========================================
- Coverage   87.11%   87.07%   -0.04%     
==========================================
  Files          47       47              
  Lines        4369     4372       +3     
  Branches      755      755              
==========================================
+ Hits         3806     3807       +1     
- Misses        405      407       +2     
  Partials      158      158              

Files	Coverage Δ
python/lsst/ctrl/mpexec/cli/script/cleanup.py	96.87% <100.00%> (ø)
python/lsst/ctrl/mpexec/cli/script/purge.py	93.00% <100.00%> (ø)
...thon/lsst/ctrl/mpexec/separablePipelineExecutor.py	94.23% <100.00%> (ø)
...ython/lsst/ctrl/mpexec/simple_pipeline_executor.py	91.22% <100.00%> (ø)
tests/test_cliCmdCleanup.py	100.00% <100.00%> (ø)
tests/test_separablePipelineExecutor.py	100.00% <100.00%> (ø)
python/lsst/ctrl/mpexec/cli/script/build.py	73.33% <0.00%> (ø)
python/lsst/ctrl/mpexec/cmdLineFwk.py	73.19% <42.85%> (-0.32%)	⬇️

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