Resolves https://github.com/elastic/kibana/issues/135035.
In this PR, I'm removing the deprecated attribute
`alerting_framework_heath` from the alerting framework health API.
## To verify
1. Start Kibana.
2. Call `/api/alerting/_health`.
3. Notice `alerting_framework_heath` is no longer part of the HTTP API
response.
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Co-authored-by: Kibana Machine <42973632+kibanamachine@users.noreply.github.com>
Co-authored-by: lcawl <lcawley@elastic.co>
