Clean up logging system properties to avoid test pollution

See gh-47424

Author: wilkinsona

core/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/SpringProfileArbiterTests.java

@@ -32,6 +32,7 @@
 import org.junit.jupiter.api.extension.ExtendWith;
 
 import org.springframework.boot.logging.LoggingInitializationContext;
+import org.springframework.boot.logging.LoggingSystemProperty;
 import org.springframework.boot.testsupport.classpath.ClassPathExclusions;
 import org.springframework.boot.testsupport.classpath.resources.WithResource;
 import org.springframework.boot.testsupport.logging.ConfigureClasspathToPreferLog4j2;
@@ -75,6 +76,9 @@ void setup(CapturedOutput output, TestInfo testInfo) {
 	void cleanUp() {
 		this.loggingSystem.cleanUp();
 		cleanUpPropertySources();
+		for (LoggingSystemProperty property : LoggingSystemProperty.values()) {
+			System.getProperties().remove(property.getEnvironmentVariableName());
+		}
 	}
 
 	@SuppressWarnings("unchecked")