add prometheus metric

[gangli113]

Fix #19324

Add a prometheus metric etcd_server_feature_enabled

Please read https://github.com/etcd-io/etcd/blob/main/CONTRIBUTING.md#contribution-flow.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @gangli113. Thanks for your PR.

I'm waiting for a etcd-io member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[gangli113]

because I added prometheus and prometheus/testutil to feature_gate.go. it requires me to run go mod tidy, otherwise build failed. The command modified go.mod and go.sum, do I need to submit these change in PR?

[siyuanfoundation]

yes, you should include the dependency changes in the PR.

[siyuanfoundation]

It seems you need to run go mod tidy in some other places as well.

[gangli113]

/cc @ahrtr

[gangli113]

sorry @ahrtr, assign to you by mistake. I was trying to add you to reviewer list.

[gangli113]

/cc @ahrtr