[CI] FollowIndexSecurityIT testCleanShardFollowTaskAfterDeleteFollower failing

[elasticsearchmachine]

Build Scans:

• elasticsearch-intake #15936 / part4
• elasticsearch-pull-request #50748 / part-4

Reproduction Line:

./gradlew ":x-pack:plugin:ccr:qa:security:follow-cluster" --tests "org.elasticsearch.xpack.ccr.FollowIndexSecurityIT.testCleanShardFollowTaskAfterDeleteFollower" -Dtests.seed=4D73614767D877A5 -Dtests.locale=de-LU -Dtests.timezone=America/Indiana/Indianapolis -Druntime.java=23

Applicable branches:
main

Reproduces locally?:
N/A

Failure History:
See dashboard

Failure Message:

java.lang.AssertionError: 
Expected: an empty collection
     but: <[{task={xpack/ccr/shard_follow_task={params={leader_shard_shard=0, headers={_xpack_security_authentication=qNGaBAAKdGVzdF9hZG1pbgEJc3VwZXJ1c2VyCgAAAAEAEGZvbGxvdy1jbHVzdGVyLTAMZGVmYXVsdF9maWxlBGZpbGUAAAAA}, leader_shard_index=.ds-logs-eu-monitor1-2025.01.16-000001, max_read_request_size=32mb, max_write_buffer_size=512mb, follow_shard_index_uuid=2H8nLzs4QlmhHqdcCXTOsg, max_write_request_operation_count=5120, max_write_buffer_count=2147483647, follow_shard_index=.ds-logs-eu-monitor1-2025.01.16-000001, leader_shard_index_uuid=kDruXIn_SS2sPqcArDlEBg, max_write_request_size=9223372036854775807b, max_retry_delay=500ms, remote_cluster=leader_cluster, max_read_request_operation_count=5120, follow_shard_shard=0, read_poll_timeout=1m, max_outstanding_read_requests=12, max_outstanding_write_requests=9}}}, assignment={explanation=node is the least loaded data node and remote cluster client, executor_node=BSVO_KxlT4GaKyxWYF_VaA}, al
[truncated]

Issue Reasons:

• [main] 2 failures in test testCleanShardFollowTaskAfterDeleteFollower (0.4% fail rate in 522 executions)

Note:
This issue was created using new test triage automation. Please report issues or feedback to es-delivery.

[elasticsearchmachine]

This has been muted on branch main

Mute Reasons:

• [main] 2 failures in test testCleanShardFollowTaskAfterDeleteFollower (0.4% fail rate in 522 executions)

Build Scans:

• elasticsearch-intake #15936 / part4
• elasticsearch-pull-request #50748 / part-4

[elasticsearchmachine]

Pinging @elastic/es-distributed-indexing (Team:Distributed Indexing)