[CI] RecoverySourceHandlerTests testSeqNoBasedRecoveryRecoversFromFallbackPlanAfterAFailure failing

[masseyke]

Build scan:
https://gradle-enterprise.elastic.co/s/n2tkjnpwe7gri/tests/:server:test/org.elasticsearch.indices.recovery.RecoverySourceHandlerTests/testSeqNoBasedRecoveryRecoversFromFallbackPlanAfterAFailure

Reproduction line:
./gradlew ':server:test' --tests "org.elasticsearch.indices.recovery.RecoverySourceHandlerTests.testSeqNoBasedRecoveryRecoversFromFallbackPlanAfterAFailure" -Dtests.seed=2ECBBD728F63B256 -Dtests.locale=ar-TN -Dtests.timezone=Pacific/Wake -Druntime.java=8

Applicable branches:
7.x

Reproduces locally?:
Yes

Failure history:
https://gradle-enterprise.elastic.co/scans/tests?tests.container=org.elasticsearch.indices.recovery.RecoverySourceHandlerTests&tests.test=testSeqNoBasedRecoveryRecoversFromFallbackPlanAfterAFailure

Failure excerpt:

java.lang.Exception: Test abandoned because suite timeout was reached.

  at __randomizedtesting.SeedInfo.seed([2ECBBD728F63B256]:0)

[elasticmachine]

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

[masseyke]

I ran into this while troubleshooting my own PR. It looks like the problem is that RecoverySourceHandlerTests::generateFiles can generate to files with the same checksum. So one copy winds up in sourceFilesToRecover and another in snapshotFilesToRecover.