feat: optimize findCertificateByName query

- to take advantage of the new DB ndex on the name_lowercase
column

[https://vmw-jira.broadcom.net/browse/TPCF-26571]

components/credentials/src/main/kotlin/org/cloudfoundry/credhub/repositories/CredentialRepository.kt

@@ -36,7 +36,7 @@ interface CredentialRepository : JpaRepository<Credential?, UUID?> {
         value = "select credential.uuid, credential.name, credential.name_lowercase, credential.checksum from certificate_credential " +
             "left join credential_version on certificate_credential.uuid = credential_version.uuid " +
             "join credential on credential.uuid = credential_version.credential_uuid " +
-            "where credential.name = ?1 limit 1 ",
+            "where credential.name_lowercase = lower(?1) limit 1 ",
         nativeQuery = true,
     )
     fun findCertificateByName(name: String?): Credential?