Allow use of snapshot repos to be disabled

Previously, the Ivy-based Grape engine used a system property,
disableSpringSnapshotRepos, to control whether or not Spring's
snapshot and milestone repositories were used for dependency
resolution. This commit adds the same capability to AetherGrapeEngine.

[#59489826]

spring-boot-cli/src/test/java/org/springframework/boot/cli/SampleIntegrationTests.java

@@ -49,7 +49,6 @@ public class SampleIntegrationTests {
 	@BeforeClass
 	public static void cleanGrapes() throws Exception {
 		GrapesCleaner.cleanIfNecessary();
-		// System.setProperty("ivy.message.logger.level", "3");
 	}
 
 	@Rule