Removes unused snapshot errors

[brooksprumo]

Problem

There are unused snapshot errors that wrap a std::io::Error. These ones in particular can be annoying when printing, because sometimes the source error (i.e. std::io::Error) does include its source in the error message, and sometimes it does not. This makes logging errors inconsistent.

Longterm, we'll have specific errors for each case, and thus will not have this ambiguity. In the meantime, prevent new uses of ambiguous IO errors.

Summary of Changes

• Removes unused SnapshotNewFromDirError::Io variant
• Removes unused SnapshotError::IoWithSourceAndFile variant

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3fa44e6) 81.8% compared to head (f6973a9) 81.8%.
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #34812   +/-   ##
=======================================
  Coverage    81.8%    81.8%           
=======================================
  Files         825      825           
  Lines      223134   223130    -4     
=======================================
+ Hits       182534   182535    +1     
+ Misses      40600    40595    -5     

[apfitzge]

lgtm - pr simply removes unused error variants.