[milvus] Support custom annotations in pod deployments

[jubingc]

What this PR does / why we need it:

To support datadog container autodiscovery, we need annotations attached directly to pods. The existing helm chart only supports custom annotations attached to services.

https://docs.datadoghq.com/containers/kubernetes/prometheus/

Checklist

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

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

[sre-ci-robot]

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

[haorenfsa]

@jubingc Thank you for bringing this patch! Please sign of your commits before we could merge it. see: https://github.com/zilliztech/milvus-helm/pull/138/checks?check_run_id=32317349030

[jubingc]

@jubingc Thank you for bringing this patch! Please sign of your commits before we could merge it. see: https://github.com/zilliztech/milvus-helm/pull/138/checks?check_run_id=32317349030

Thanks for the pointer. Commits have been signed off now.

[haorenfsa]

/lgtm

[haorenfsa]

/approve

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: haorenfsa, jubingc

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