Unmute FollowingEngineTests:: testProcessOnceOnPrimary (#128955)

A fix was separately submitted.

Author: kkrik-es

muted-tests.yml

@@ -465,9 +465,6 @@ tests:
 - class: org.elasticsearch.xpack.esql.plugin.DataNodeRequestSenderIT
   method: testSearchWhileRelocating
   issue: https://github.com/elastic/elasticsearch/issues/128500
-- class: org.elasticsearch.xpack.ccr.index.engine.FollowingEngineTests
-  method: testProcessOnceOnPrimary
-  issue: https://github.com/elastic/elasticsearch/issues/128541
 - class: org.elasticsearch.xpack.esql.action.CrossClusterQueryWithPartialResultsIT
   method: testFailToStartRequestOnRemoteCluster
   issue: https://github.com/elastic/elasticsearch/issues/128545