[hotfix] Simplify the checkpointStatsSnapshotCacheExpireAfterWrite (#26349)

Author: beliefer

flink-runtime/src/main/java/org/apache/flink/runtime/rest/handler/RestHandlerConfiguration.java

@@ -114,9 +114,7 @@ public static RestHandlerConfiguration fromConfiguration(Configuration configura
 
         final int checkpointHistorySize = configuration.get(WebOptions.CHECKPOINTS_HISTORY_SIZE);
         final Duration checkpointStatsSnapshotCacheExpireAfterWrite =
-                configuration
-                        .getOptional(RestOptions.CACHE_CHECKPOINT_STATISTICS_TIMEOUT)
-                        .orElse(Duration.ofMillis(refreshInterval));
+                configuration.get(RestOptions.CACHE_CHECKPOINT_STATISTICS_TIMEOUT);
         final int checkpointStatsSnapshotCacheSize =
                 configuration.get(RestOptions.CACHE_CHECKPOINT_STATISTICS_SIZE);
 

flink-runtime/src/test/java/org/apache/flink/runtime/rest/handler/RestHandlerConfigurationTest.java

@@ -106,12 +106,16 @@ private static void testWebCancelFeatureFlag(boolean webCancelEnabled) {
 
     @Test
     void testCheckpointCacheExpireAfterWrite() {
-        final Duration testDuration = Duration.ofMillis(100L);
         final Configuration config = new Configuration();
-        config.set(RestOptions.CACHE_CHECKPOINT_STATISTICS_TIMEOUT, testDuration);
-
+        final Duration defaultDuration = Duration.ofMillis(3000L);
         RestHandlerConfiguration restHandlerConfiguration =
                 RestHandlerConfiguration.fromConfiguration(config);
+        assertThat(restHandlerConfiguration.getCheckpointCacheExpireAfterWrite())
+                .isEqualTo(defaultDuration);
+
+        final Duration testDuration = Duration.ofMillis(100L);
+        config.set(RestOptions.CACHE_CHECKPOINT_STATISTICS_TIMEOUT, testDuration);
+        restHandlerConfiguration = RestHandlerConfiguration.fromConfiguration(config);
         assertThat(restHandlerConfiguration.getCheckpointCacheExpireAfterWrite())
                 .isEqualTo(testDuration);
     }