Add support for custom build pipeline

[yuzs2]

Hi, I'm working on milvus-operator deployment in a private cloud environment. To fit our environment, I need to re-edit the milvus dependency helm charts (etcd, minio, pulsar, etc.) and re-build the image.

To re-build the image, I must customize the Dockerfile and Makefile, and then run make docker-build. It's not an elegant way, and it would be very hard to track the latest milvus-operator release with the pipeline. Could you please add the support for custom build in your Makefile? It would be easily to accomplish by adding something like make docker-build-with-helmcharts {Path}. Thank you.

[haorenfsa]

Yes, it’s a reasonable feature. Would you like to launch a PR yourself?

[yuzs2]

@haorenfsa Yes, I can create the PR this time. But the problem would be in the future. I can see you are using the same helm charts in the recent releases, and I customize the helm charts based on them. But in the future release, would you bump your helm charts version? If so, how can we guarantee the custom helm charts would still work with the new release?

Would you like to share some roadmap/plan about your helm-charts maintenance?

[haorenfsa]

@yuzs2 The version of the dependency charts are maintained in another repo, you can see the history there https://github.com/zilliztech/milvus-helm/commits/master/charts/milvus/charts. Usually we only change them when there're some vulnerability issues or other necessary optimizations. Considering about the stability, the changes will be small, and compatible with previous versions.