Adjust maximum value for memory_share_for_fetch in MemoryStressTest.test_fetch_with_many_partitions

[dlex]

The failing case is OOM when memory reserved for fetch is 80% of kafka memory, but apparently some knobs in memory control do not reflect what is going on with allocations indeed. For this specific test, the setting should go down gradually until this crash is gone, and that should become the highest recommended setting for now.

Getting it down to 0.7.

Fixes #11458

Backports Required

• none - not a bug fix
• none - this is a backport
• none - issue does not exist in previous branches
• none - papercut/not impactful enough to backport
• v23.1.x
• v22.3.x
• v22.2.x

Release Notes

• none

[dlex]

CI failures in https://buildkite.com/redpanda/redpanda/builds/31611#0188d489-fb1c-4494-ad16-477c664829b7 are not relevant

[michael-redpanda]

This seems fine. My only question is was there a reason 0.8 was selected in the past? Are we just putting a band-aid over an actual problem by reducing this?

[dlex]

@michael-redpanda 0.8 was the maxiumum that allowed to avoid OOM, but apparently that's not right (see this comment). Re the band-aid, the memory semaphore solution is a band-aid, see this.

[dlex]

All CI failures are irrelevant

[michael-redpanda]

CI Issues:

• CI Failure (timeout in kafka-topics.sh create topic) in RackAwarePlacementTest.test_replica_placement in DEBUG builds #11276
• CI Failure (Timeout: Leadership did not stablize) in MultiTopicAutomaticLeadershipBalancingTest.test_topic_aware_rebalance #11454 (closed after CI run)

[vbotbuildovich]

/backport v23.1.x

[vbotbuildovich]

/backport v22.3.x

[vbotbuildovich]

Failed to run cherry-pick command. I executed the commands below:

git checkout -b backport-pr-11533-v23.1.x-557 remotes/upstream/v23.1.x
git cherry-pick -x 51b3333a0bedb061307e422a0790bed0ef67f3d0

Workflow run logs.

[vbotbuildovich]

Failed to run cherry-pick command. I executed the commands below:

git checkout -b backport-pr-11533-v22.3.x-438 remotes/upstream/v22.3.x
git cherry-pick -x 51b3333a0bedb061307e422a0790bed0ef67f3d0

Workflow run logs.