[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.]

• [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

[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

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/zilliztech/milvus-helm/blob/master/OWNERS)~~ [haorenfsa] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment