add attendance#trial_lessons method
[#76155838] red spec identifying bug
[#76155838]remove localeapp
[#76155838]update bin
[#76155838]avoid nil
[#76155838]use attendance#trial_lessons
[#76155838] sqlite3 compatible implementation

- refactor TimeSlow .with_schedule and .without_schedule
with a SQL implementation that is compatible with sqlite3
Merge 76155838-bug to master

[Completes #76155838]