ref: decrease Kafka log retention hours

[aldy505]

This is coming from a discussion from @jan-auer on Slack. He figured that it would be fine (or perhaps better) if the retention hours is set to 1 hour. I have a personal argument that 1 hour might not be enough for folks running in bigger volume and therefore slower processing time, therefore this 3 hours is a compromise.

To apply the change, the easiest way is to delete the Kafka volume, and let the install.sh script recreate it. But you can also do it manually using the kafka CLI:

for topic in $(docker compose exec kafka kafka-topics \
  --bootstrap-server kafka:9092 \
  --list); do
  docker compose exec kafka kafka-configs \
    --bootstrap-server kafka:9092 \
    --entity-type topics \
    --entity-name $topic \
    --alter \
    --add-config retention.ms=86400000
done

[sentry]

Bug: The manual migration script in the PR description uses an incorrect retention.ms value (24 hours) instead of the intended 3 hours.
_{Severity: MEDIUM}

Suggested Fix

In the pull request description, correct the manual migration command to use retention.ms=10800000 instead of retention.ms=86400000 to align with the intended 3-hour retention period.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: docker-compose.yml#L216

Potential issue: The manual migration script provided in the pull request description
contains an incorrect value. It instructs users to set `retention.ms` to `86400000`,
which is 24 hours, instead of the intended 3 hours. Users who follow this manual
migration path will not get the benefit of the reduced log retention, as the topic-level
configuration will override the new 3-hour broker-level default. This undermines the
primary goal of the pull request, which is to reduce disk usage.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[aminvakil]

For small data volumes, 1 hour and 3 hours do not make much of a difference.

I would say let's make 3 hours default and keep higher value note below.