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On request of @jburr to make this easier to understand and teach for
beginners.  Note that this involved a fair amount of whitespace
changes to make the for-body indentation consistent with the rest of
each file.

Essentially when we are using a decoration handle we should not need
to make a copy, but be able to directly decorate the input object.

There are probably other common CP algorithms that could be switched
from `SysCopyHandle` to `SysReadHandle`, but this is the lowest
hanging fruit.

Adding ifdef statement to DiTauSmearingAlg so that it is
skipped in compilation. The Alg should be brought back
after TauAnalysisTools migration from R21.2

TauAnalysisAlgorithms/DiTauSmearingAlg.cxx depends
on DiTauSmearingAlg which is not migrated from R21.2 yet.
This fix removes the DiTauSmearingAlg from compilation,
which should be added back once TauAnalysisTools is
properly migrated.

Originally I had tried sweeping/cherry-picking this from 21.2, but
with all the three-way merges and commits that involve other
packages/directories that was rather painful, so this is now just a
direct copy from the current state in 21.2.