Ignore JUnit annotations when caching test contexts

Update `ImportsContextCustomizer` to ignore JUnit annotations.

See gh-28563

spring-boot-project/spring-boot-test/src/main/java/org/springframework/boot/test/context/ImportsContextCustomizer.java

@@ -222,6 +222,7 @@ class ImportsContextCustomizer implements ContextCustomizer {
 			filters.add(new JavaLangAnnotationFilter());
 			filters.add(new KotlinAnnotationFilter());
 			filters.add(new SpockAnnotationFilter());
+			filters.add(new JunitAnnotationFilter());
 			ANNOTATION_FILTERS = Collections.unmodifiableSet(filters);
 		}
 
@@ -384,4 +385,15 @@ class ImportsContextCustomizer implements ContextCustomizer {
 
 	}
 
+	/**
+	 * {@link AnnotationFilter} for Spock annotations.
+	 */
+	private static final class JunitAnnotationFilter implements AnnotationFilter {
+
+		@Override
+		public boolean isIgnored(Annotation annotation) {
+			return annotation.annotationType().getName().startsWith("org.junit.");
+		}
+
+	}
 }