Refactor functions to use piping for Ecto queries

[GabrielCWT]

In order to stay consistent with formatting, these functions should use piping.

• [ ] get_notification_config!
• [ ] get_time_options_for_assessment
• [ ] get_default_time_option_for_assessment!
• [ ] get_notification_preference
• [ ] write_notification_when_published
• [ ] all_student_enrolled_in_course
• [ ] student_already_in_team?
• [ ] get_submission_ids
• [ ] find_team
• [ ] find_teams
• [ ] unsubmit_submission
• [ ] team_controller/index