Development: Fix flaky ExerciseScoresChartIntegrationTest

[DominikRemo]

Checklist

General

• The changed server tests succeed locally and on Bamboo and on GitHub Actions.
• Language: I followed the guidelines for inclusive, diversity-sensitive, and appreciative language.
• I chose a title conforming to the naming conventions for pull requests.

Server

• I followed the coding and design guidelines.

Motivation and Context

The test in ExerciseScoresChartIntegrationTest was flaky. The test's setup method contains multiple awaits that regularly timed out for MySQL and Postgres because of many scheduled tasks and slower database access.

Description

The test is fixed by setting lastScheduledRun in ParticipantScoreScheduleService. Setting the value to Instant.now() prevents the ScheduleService from calculating the scores of results unrelated to this tests (Results created in prior tests).

MySQL run without failing ExerciseScoresChartIntegrationTest:
https://github.com/ls1intum/Artemis/actions/runs/6407425948/job/17394178642

Postgres run without failing ExerciseScoresChartIntegrationTest:
https://github.com/ls1intum/Artemis/actions/runs/6407425948/job/17424739364 (Test succeeded before job was canceled [see logs])

Steps for Testing

Test changes only

Review Progress

Code Review

• Code Review 1
• Code Review 2

[laadvo]

Tests now succeed against mysql and postgres, nice fix 👍

[Strohgelaender]

lgtm

Would it make sense to merge this and the other PRs with similar fixes into one PR? This would make it easier to check the MySQL-build status and verify that all these tests now work.