[CELEBORN-1931][FOLLOWUP] Update config version for worker local flusher gather api

### What changes were proposed in this pull request?

Update the config version to 0.5.5 for `celeborn.worker.flusher.local.gatherAPI.enabled`.

### Why are the changes needed?
Followup https://github.com/apache/celeborn/pull/3335

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?

GA

Closes #3338 from turboFei/CELEBORN-1931_follow.

Authored-by: Wang, Fei <fwang12@ebay.com>
Signed-off-by: Wang, Fei <fwang12@ebay.com>

common/src/main/scala/org/apache/celeborn/common/CelebornConf.scala

@@ -3994,7 +3994,7 @@ object CelebornConf extends Logging {
     buildConf("celeborn.worker.flusher.local.gatherAPI.enabled")
       .internal
       .categories("worker")
-      .version("0.6.0")
+      .version("0.5.5")
       .doc("Worker will use gather API if this config is true.")
       .booleanConf
       .createWithDefault(true)