chore: 중복 인덱스 생성 방지를 위해 인덱스 생성 제거

- FK 제약조건을 추가할 때 인덱스가 없다면 알아서 추가하기 때문

Author: whqtker

src/main/resources/db/migration/V42__rename_university_to_host_university_and_create_home_university.sql

@@ -21,5 +21,3 @@ ALTER TABLE host_university
 ALTER TABLE host_university
     ADD CONSTRAINT fk_host_university_home_university
         FOREIGN KEY (home_university_id) REFERENCES home_university (id) ON DELETE NO ACTION;
-
-CREATE INDEX fk_host_university_home_university_idx ON host_university (home_university_id);