Remove reflection hints for default Logback converters

[bclozel]

As of #31687, the Spring Boot build plugins now use the GraalVM reachability metadata repository as a source of metadata.
Since #30975, the Spring Boot team has contributed hints to the community, including reflection for the default Logback converters. As the file and syslog appenders are not considered by default there, we still need to register those in the Spring Boot runtime hints.

We should here remove the duplicate reflection entries.