use concurrency safe primitive. (#11404)

Related to https://airbytehq-team.slack.com/archives/C03AS1GAQV6/p1708704237474249.

I believe this is why we are throwing an error.

Note that Java doesn't provide a concurrency safe Hashset out of the box. The general recommendation is to use the Concurrent Hashmap Key set.

airbyte-commons-worker/src/main/java/io/airbyte/workers/internal/FieldSelector.java

@@ -183,7 +183,7 @@ private void validateSchemaUncounted(final AirbyteMessage message) {
     recordSchemaValidator.validateSchemaWithoutCounting(record, messageStream, uncountedValidationErrors);
     final Set<String> unexpectedFieldNames = getUnexpectedFieldNames(record, streamToAllFields.get(messageStream));
     if (!unexpectedFieldNames.isEmpty()) {
-      unexpectedFields.computeIfAbsent(messageStream, k -> new HashSet<>()).addAll(unexpectedFieldNames);
+      unexpectedFields.computeIfAbsent(messageStream, k -> ConcurrentHashMap.newKeySet()).addAll(unexpectedFieldNames);
     }
   }