test: DataSource 학습 테스트에서 설정 하드코딩 제거 및 properties 로드 적용#961

Starlight258 wants to merge 4 commits intowoowacourse:mainwoowacourse/java-jdbc:mainfrom

Starlight258:test/jdbcStarlight258/java-jdbc:test/jdbcCopy head branch name to clipboard