model/xos: filter perodic save schedule time

[sargon]

Pre-Request Checklist

• Passes rubocop code analysis (try rubocop --auto-correct)
• Tests added or adapted (try rake test)
• Changes are reflected in the documentation
• User-visible changes appended to CHANGELOG.md

Description

Filter the next periodic schedule time from configuration output. In our case that line triggered a change several times a day.

[codecov-commenter]

Codecov Report

Merging #2169 into master will decrease coverage by 0.13%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2169      +/-   ##
==========================================
- Coverage   63.32%   63.19%   -0.14%     
==========================================
  Files          30       30              
  Lines        1497     1497              
==========================================
- Hits          948      946       -2     
- Misses        549      551       +2     

Impacted Files	Coverage Δ
lib/oxidized/output/git.rb	17.35% <0.00%> (-1.66%)	⬇️

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[wk]

Pulling this in, thanks!