MINOR; Add `--standalone --ignore-formatted` formatter test (#19643)

This PR adds an additional test case to `FormatterTest` that checks that
formatting with `--standalone` and then formatting again with
`--standalone --ignore-formatted` is indeed a no-op.

Reviewers: José Armando García Sancio <jsancio@apache.org>

metadata/src/test/java/org/apache/kafka/metadata/storage/FormatterTest.java

@@ -192,6 +192,39 @@ public class FormatterTest {
         }
     }
 
+    @Test
+    public void testStandaloneWithIgnoreFormatted() throws Exception {
+        try (TestEnv testEnv = new TestEnv(1)) {
+            FormatterContext formatter1 = testEnv.newFormatter();
+            String originalDirectoryId = Uuid.randomUuid().toString();
+            String newDirectoryId = Uuid.randomUuid().toString();
+            formatter1.formatter
+                .setInitialControllers(DynamicVoters.parse("1@localhost:8020:" + originalDirectoryId))
+                .run();
+            assertEquals("Formatting dynamic metadata voter directory " + testEnv.directory(0) +
+                    " with metadata.version " + MetadataVersion.latestProduction() + ".",
+                formatter1.output().trim());
+            assertMetadataDirectoryId(testEnv, Uuid.fromString(originalDirectoryId));
+
+            FormatterContext formatter2 = testEnv.newFormatter();
+            formatter2.formatter
+                .setIgnoreFormatted(true)
+                .setInitialControllers(DynamicVoters.parse("1@localhost:8020:" + newDirectoryId))
+                .run();
+            assertEquals("All of the log directories are already formatted.",
+                formatter2.output().trim());
+            assertMetadataDirectoryId(testEnv, Uuid.fromString(originalDirectoryId));
+        }
+    }
+
+    private void assertMetadataDirectoryId(TestEnv testEnv, Uuid expectedDirectoryId) throws Exception {
+        MetaPropertiesEnsemble ensemble = new MetaPropertiesEnsemble.Loader().
+            addLogDirs(testEnv.directories).
+            load();
+        MetaProperties logDirProps0 = ensemble.logDirProps().get(testEnv.directory(0));
+        assertEquals(expectedDirectoryId, logDirProps0.directoryId().get());
+    }
+
     @Test
     public void testOneDirectoryFormattedAndOthersNotFormatted() throws Exception {
         try (TestEnv testEnv = new TestEnv(2)) {