Change default for event-name flags to `true` in 3.0 release

[trask]

In PR #14649, support was added to capture event names in logging instrumentation. The feature was initially introduced with the default value of false to avoid breaking changes.

For the 3.0 release, I think it makes sense to change the default value from false to true based on open-telemetry/semantic-conventions#2715.

Configuration Flags to Update

• otel.instrumentation.jboss-logmanager.experimental.capture-event-name
• otel.instrumentation.log4j-appender.experimental.capture-event-name (both 1.2 and 2.17 javaagent)
• otel.instrumentation.logback-appender.experimental.capture-event-name (javaagent)
• captureEventName builder property (Log4j 2.17 and Logback 1.0 library appenders)

Documentation to Update

README files that document these flags:

• instrumentation/jboss-logmanager/README.md
• instrumentation/log4j/log4j-appender-1.2/javaagent/README.md
• instrumentation/log4j/log4j-appender-2.17/javaagent/README.md
• instrumentation/log4j/log4j-appender-2.17/library/README.md
• instrumentation/logback/logback-appender-1.0/javaagent/README.md
• instrumentation/logback/logback-appender-1.0/library/README.md