Fix flaky test by isolating tests that modify user.home (#6574)

MavenSecuritySettingsTest and MavenSettingsTest modify the global
user.home system property during tests. With parallel test execution
enabled, other tests could pick up the modified property pointing to
an empty temp directory, causing parse failures.

Added @isolated annotation to ensure these tests run alone.

Author: jkschneider

rewrite-maven/src/test/java/org/openrewrite/maven/MavenSecuritySettingsTest.java

@@ -21,6 +21,7 @@
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.api.parallel.Execution;
 import org.junit.jupiter.api.parallel.ExecutionMode;
+import org.junit.jupiter.api.parallel.Isolated;
 import org.openrewrite.InMemoryExecutionContext;
 
 import java.io.IOException;
@@ -29,6 +30,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+@Isolated("Modifies user.home system property")
 @Execution(ExecutionMode.SAME_THREAD)
 class MavenSecuritySettingsTest {
 

rewrite-maven/src/test/java/org/openrewrite/maven/MavenSettingsTest.java

@@ -28,6 +28,7 @@
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.api.parallel.Execution;
 import org.junit.jupiter.api.parallel.ExecutionMode;
+import org.junit.jupiter.api.parallel.Isolated;
 import org.openrewrite.InMemoryExecutionContext;
 import org.openrewrite.Issue;
 import org.openrewrite.Parser;
@@ -49,6 +50,7 @@
 import static org.assertj.core.api.Assertions.assertThat;
 
 @SuppressWarnings({"HttpUrlsUsage", "ConstantConditions", "OptionalGetWithoutIsPresent"})
+@Isolated("Modifies user.home system property")
 @Execution(ExecutionMode.SAME_THREAD)
 class MavenSettingsTest {