Previously, the import selector for `@ImportAutoConfiguration` did not
consider the spring.autoconfigure.exclude property when determining
which auto-configurations to exclude. This meant that tests using a
slice that included a particular auto-configuration would include it
even if the application's configuration excluded it via
spring.autoconfigure.exclude. Confusingly, this could result in a
sliced test using an auto-configuration that would be excluded in a
broader `@SpringBootTest`.

This commit updates the ImportAutoConfigurationImportSelector to
consider the spring.autoconfigure.exclude property so that sliced tests
will use a subset of the auto-configurations that a `@SpringBootTest`
would use.

Fixes gh-21736