[bitnami/kafka] Update default value of heapOpts to fit Kafka pod RAM limit while utilize its increase (#29670)

[plblueraven]

Description of the change

OK, here we go:

1. You are using bitnami/minideb as base image. Unfortunately, I couldn't find any minimum requirements for this image in the README.md, therefore I assume minimal requirements of Debian itself which is 256 MB.
2. Estimating the minimum RAM for Kafka for a development environment isn't an easy task. I found a lot of opinion based data. The only ones I consider valuable are: a) Kafka server startup script with 1G is set as Xmx; b) competitive, unofficial, helm chart where we have cp-kafka.heapOptions with Xmx set to 512M.
3. You are using Java 17, on which (in the case of Linux distributions) -XX:+UseContainerSupport is enabled by default. In this case we could benefit from setting -XX:InitialRAMPercentage and -XX:MaxRAMPercentage

As in commit I suggest removing -Xmx1024m -Xms1024m and replacing it with -XX:InitialRAMPercentage=75 -XX:MaxRAMPercentage=75. This will ensure 256 MB for the OS (768 MB*(1-0.75)=256 MB) and sort of solve the problem of scaling RAM available for Kafka with increasing Containers.kafka.Limits.memory value.

Benefits

• Bothering Kubernetes' OOM Killer is much less likely.
• RAM avaialble for Kafka will automatically scale with Kafka pod RAM limit

Possible drawbacks

Kafka could be inefficient at default 768 MB*0.75=512 MB RAM.

Applicable issues

• fixes [bitnami/kafka] Wrong default value of Xmx in context of default value of Containers.kafka.Limits.memory #29670

Additional information

This needs testing, which I cannot do with a satisfactory variety of traffic.

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
• Title of the pull request follows this pattern [bitnami/<name_of_the_chart>] Descriptive title
• All commits signed off and in agreement of Developer Certificate of Origin (DCO)

[dgomezleon]

LGTM. Thanks for contributing!