CORE-1752: cst: improved logging

[abhijat]

Adds more logging around chunk hydration to investigate stuck readers. Does not fix the attached issue #16465

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
• v23.3.x
• v23.2.x

Release Notes

• none

[vbotbuildovich]

new failures in https://buildkite.com/redpanda/redpanda/builds/47651#018ecc46-9469-4e6a-ae1a-b1fb75a551d9:

"rptest.tests.cloud_storage_timing_stress_test.CloudStorageTimingStressTest.test_cloud_storage_with_partition_moves.cleanup_policy=delete"

[vbotbuildovich]

/backport v23.3.x

[vbotbuildovich]

/backport v23.2.x

[vbotbuildovich]

Failed to create a backport PR to v23.2.x branch. I tried:

git remote add upstream https://github.com/redpanda-data/redpanda.git
git fetch --all
git checkout -b backport-pr-17785-v23.2.x-211 remotes/upstream/v23.2.x
git cherry-pick -x 963a5d3e30abd2a9714d84cd098afd442a486cae 33eeca9b05452b7fde1d13898008c334c87c3c4d

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