Magma S0 tests on 7.0 hit out of memory issue

In Magma S0 tests on 7.0, I saw this message showed up repeatedly.

[2020-07-24 19:07:20,185: WARNING/Process-1:54] Function: update, error: <Key='367e2a-0fb68434df432b95ef4f91b655f373cb9210', RC=0x8[The server is out of memory. Try again later], Operational Error, Results=1, C Source=(src/multiresult.c,316), Tracing Output={"367e2a-0fb68434df432b95ef4f91b655f373cb9210": null}>

Build: 7.0.0-2635

Job: http://perf.jenkins.couchbase.com/job/rhea-5node1/129/

Logs:

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-rhea-5node1-129/172.23.97.21.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-rhea-5node1-129/172.23.97.22.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-rhea-5node1-129/172.23.97.23.zip

https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-rhea-5node1-129/172.23.97.24.zip

I did a run with cursor_dropping_checkpoint_mem_upper_mark=100, and the issue is gone.

Job: http://perf.jenkins.couchbase.com/job/rhea-5node1/132/