Exclude ImportControl checkstyle rule from samples

See gh-14660

Author: philwebb

src/checkstyle/checkstyle-suppressions.xml

@@ -15,6 +15,7 @@
 	<suppress files="[\\/]autoconfigure[\\/]" checks="JavadocVariable" />
 	<suppress files="[\\/]spring-boot-docs[\\/]" checks="JavadocType" />
 	<suppress files="[\\/]spring-boot-samples[\\/]" checks="JavadocType" />
+	<suppress files="[\\/]spring-boot-samples[\\/]" checks="ImportControl" />
 	<suppress files="[\\/]spring-boot-deployment-tests[\\/]" checks="JavadocType" />
 	<suppress files="[\\/]spring-boot-integration-tests[\\/]" checks="JavadocType" />
 	<suppress files="Ansi.*\.java" checks="JavadocVariable" />