fix(mixin): Fix alerts aggregation by improving config defaults

[v-zhuravlev]

If not all labels are mentioned you might get 3 similar alerts (as etcdInsufficientMembers) instead of just one per cluster.

pod and instance are always present in typical k8s prometheus setups so best to provide those as defaults , so alerts work properly in most cases.

[k8s-ci-robot]

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[k8s-ci-robot]

Hi @v-zhuravlev. Thanks for your PR.

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[k8s-ci-robot]

@v-zhuravlev: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

Hi @v-zhuravlev. Thanks for your PR.

I'm waiting for a github.com 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.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

/ok-to-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[ahrtr]

pls see comment right above the config item.

Users may also run etcd in non-K8s environment.