FIX: RecordCommonStatsJob Correctly Saves Stats in Repository

[iain801]

Overview

In this PR, we fix the functionality of CommonStats so that the stats are saved into the repository when the job is run.

Tests

• [x] Backend Unit tests (mvn test) pass
• [x] Backend Test coverage (mvn test jacoco:report) 100%
• [x] Backend Mutation tests (mvn test pitest:mutationCoverage) 100%