Development: Fix flaky ResultListenerIntegrationTest

[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 tests in ResultListenerIntegrationTest were flaky. The tests' failed against MySQL and Postgres because of many scheduled tasks and slower database access.

Description

The tests are 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). Additionally, the schedule delay has been increased to account for slower database access.

MySQL run without failing ResultListenerIntegrationTest(s):
https://github.com/ls1intum/Artemis/actions/runs/6419281166/job/17428804520?pr=7326

Postgres run without failing ResultListenerIntegrationTest(s):
https://github.com/ls1intum/Artemis/actions/runs/6419281166/job/17428804757?pr=7326

Steps for Testing

Test changes only

Review Progress

Code Review

• Code Review 1
• Code Review 2

[laadvo]

Flaky test fix LGTM