Reuse prepared query, increase pool size, cleanup

[eivanov89]

No description provided.

[KirillKurdyukov]

@Repository
class YdbRepository {

    @Autowired
    lateinit var entityManager: EntityManager

    @Transactional(readOnly = true)
    fun getFixedString(s: String): String {
        return entityManager.createNativeQuery("SELECT ?1")
                .setParameter(1, s)
                .singleResult.toString()
    }
}