[milvus] Change kafka as default MQ

[dongjiang1989]

What this PR does / why we need it:

Change kafka as default MQ.

Originally posted by https://milvus.io/tools/sizing

1 Million of vectors, 128 Dimensions with 512MB segment

Pulsar:

kafka:

	Pulsar	kafka
CPU	40Core	32Core
Memory	167GB	112GB
SSD	240GB	150GB
Disk	70GB	70GB

Checklist

[Place an '[x]' (no spaces) in all applicable fields. Please remove unrelated fields.]

• [x] Chart Version bumped
• [x] Variables are documented in the README.md
• [x] Title of the PR starts with chart name (e.g. [mychartname])
• [x] PR only contains changes for one chart

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[sre-ci-robot]

Welcome @dongjiang1989! It looks like this is your first PR to zilliztech/milvus-helm 🎉

[haorenfsa]

Thank you @dongjiang1989 for bring this out. But it's unlikely we change the default MQ, because many people still uses pulsar and will otherwise be affected next time they do update.

[haorenfsa]

By the way, if you have more data or collections or instances, pulsar usually cost less in our practice.

[dongjiang1989]

By the way, if you have more data or collections or instances, pulsar usually cost less in our practice.

Thanks. In my business scenario, using kafka lower usage cost (muti instances in one Kubernetes Cluster). Is there any chance to kafka as default MQ?

[haorenfsa]

@dongjiang1989 Sry, it's a no.

[LoveEachDay]

@dongjiang1989 You can manually set kafka as your preferences via simple --set or specify in values.yaml. We'd like to keep pulsar as the default option for milvus cluster.