Ensure that Quartz can be auto-configured with a Quartz-specific TM

Previously, Quartz could be configured with a specific DataSource
using `@QuartzDataSource` but it was not possible to configure a
Quartz-specific transaction manager. This could result in the
different DataSources being used by Quartz itself and Quart'z
DataSourceTransactionManager.

This commit introduces a new qualifier, `@QuartzTransactionManager`,
that can be used to avoid the above-described problem. Any
`@QuartzTransactionManager`-annotated bean will be used by the
Quartz auto-configure configuration instead of the application's main
`TransactionManager`. If no such qualified bean is present, the
application's main TransactionManager, if any, will be used as before.

Fixes gh-20184

spring-boot-project/spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -5819,6 +5819,7 @@ It is also possible to provide a custom script by setting the configprop:spring.
 
 To have Quartz use a `DataSource` other than the application's main `DataSource`, declare a `DataSource` bean, annotating its `@Bean` method with `@QuartzDataSource`.
 Doing so ensures that the Quartz-specific `DataSource` is used by both the `SchedulerFactoryBean` and for schema initialization.
+Similarly, to have Quartz use a `TransactionManager` other than the application's main `TransactionManager` declare a `TransactionManager` bean, annotating its `@Bean` method with `@QuartzTransactionManager`.
 
 By default, jobs created by configuration will not overwrite already registered jobs that have been read from a persistent job store.
 To enable overwriting existing job definitions set the configprop:spring.quartz.overwrite-existing-jobs[] property.