[CI] SLMSnapshotBlockingIntegTests.testRetentionWhileSnapshotInProgress failing

[mark-vieira]

org.elasticsearch.xpack.slm.SLMSnapshotBlockingIntegTests.testRetentionWhileSnapshotInProgress has started failing pretty often now with the following error:

java.lang.AssertionError: expected at least one master-eligible node left in {node_sc1=org.elasticsearch.test.InternalTestCluster$NodeAndClient@6e458321}

Here are some example build scans:
https://gradle-enterprise.elastic.co/s/hlldgfw3cx4bc/tests/rfsroxnx4sflo-uvkkyo6qd6mno
https://gradle-enterprise.elastic.co/s/i4ncjbmiflt6a/tests/rfsroxnx4sflo-uvkkyo6qd6mno
https://gradle-enterprise.elastic.co/s/33mp5rqowzsbi/tests/rfsroxnx4sflo-uvkkyo6qd6mno

Looking at build-stats this looks to be happening in both master and 7.x.

[elasticmachine]

Pinging @elastic/es-distributed (:Distributed/Snapshot/Restore)

[mark-vieira]

This has been failing often enough that I've muted this in master and 7.x.

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/ILM+SLM)