[CELEBORN-2273] Fix cache mutation in TagsManager.getTaggedWorkers()

What changes were proposed in this pull request?
getTaggedWorkers() obtains a direct reference to the cached Set from getWorkersWithTag()and then calls retainAll() on it to intersect with other tags and available workers. Since retainAll() mutates the Set in-place, this permanently corrupts the cached entry. When multiple applications with different tag combinations share the same master, one app's intersection shrinks the cached Set, causing subsequent lookups by other apps to find fewer or zero workers. Once corrupted to an empty Set, all future slot requests fail with WORKER_EXCLUDED until the cache is refreshed.

Why are the changes needed?
Does this PR resolve a correctness bug?
Yes

Does this PR introduce any user-facing change?
No

How was this patch tested?
custom image in my dev env + local test

Closes #3615 from shlomitubul/main.

Authored-by: ShlomiTubul <shlomi.tubul@placer.ai>
Signed-off-by: SteNicholas <programgeek@163.com>

Author: shlomitubul

master/src/main/scala/org/apache/celeborn/service/deploy/master/tags/TagsManager.scala

@@ -79,7 +79,7 @@ class TagsManager(configService: Option[ConfigService]) extends Logging {
         case Some(w) =>
           w.retainAll(taggedWorkers)
         case _ =>
-          workersForTags = Some(taggedWorkers)
+          workersForTags = Some(new util.HashSet[String](taggedWorkers))
       }
     }