Backport of Fix alias check leak into release/1.13.x

[hc-github-team-consul-core]

Backport

This PR is auto-generated from #14935 to be assessed for backporting due to the inclusion of the label backport/1.13.

The below text is copied from the body of the original PR.

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Description

Preivously when alias check was removed it would not be stopped nor cleaned up from the associated aliasChecks map.

This means that any time an alias check was deregistered we would leak a goroutine for CheckAlias.run() because the stopCh would never be closed.

This issue comes up then the sidecar_service stanza is used, as documented here. When services are registered this way without custom health checks it leads to adding an alias check, which makes the sidecar service reflect the health of the underlying service.

The issue can lead to large goroutine counts in service mesh deployments on platforms where the client agent is mostly static but proxy services come and go regularly.

Testing & Reproduction steps

• Noticed leak in a goroutine profile, which had over a thousand goroutines in CheckAlias.run() but there were only about a dozen services.
• Confirmed behavior with the unit test added, which initially failed.

PR Checklist

• updated test coverage
• external facing docs updated
• not a security concern

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Overview of commits

• f4cc457 - da68ed7