Logback file not updated as part of transform

Went through the transform process from Java 8 to 21 and was unable to run the application afterward without adding a `name` attribute to the element in the logback.xml. Just wanted to mention since this is meant to be the sample and didn't work for me out of the box.

```
Caused by: java.lang.IllegalStateException: Logback configuration error detected:
ERROR in ch.qos.logback.core.joran.action.AppenderAction - Missing attribute [name] in element [appender] near line 9
at org.springframework.boot.logging.logback.LogbackLoggingSystem.reportConfigurationErrorsIfNecessary(LogbackLoggingSystem.java:277)
at org.springframework.boot.logging.logback.LogbackLoggingSystem.loadConfiguration(LogbackLoggingSystem.java:255)
at org.springframework.boot.logging.logback.LogbackLoggingSystem.reinitialize(LogbackLoggingSystem.java:334)
at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:74)
at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:61)
at org.springframework.boot.logging.logback.LogbackLoggingSystem.initialize(LogbackLoggingSystem.java:189)
at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:332)
... 19 more
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
```

Start with the transformed sample's logback.xml and inspect the element near line 9. Verify the configuration against the reported Logback error, then run the application after the Java 8-to-21 transform; done means it starts without requiring a manual name attribute change.

索引モデルが issue の本文から書いたものです。