Stack monitoring changes for Elasticsearch

[danhermann]

The following changes will be made to Elasticsearch monitoring to facilitate its inclusion in Stack Monitoring:

Pre-8.0 (7.x branches)

• Deprecate settings that for removal in 8.0
  • Ingest pipelines Deprecate the Monitoring ingest settings #77659 Add deprecation info API entries for deprecated monitoring settings #78799
  • Legacy Templates Deprecate create_legacy_templates setting on HTTP Exporters #78564 Add deprecation info API entries for deprecated monitoring settings #78799
  • All Monitoring settings Deprecate Monitoring Settings #79499
• Provide an upgrade path during the 7.x timeline to replace Watcher alerts with Kibana alerting. Provide migration path for monitoring alerting from Watcher to Kibana alerting  #50032 Add setting to decommission legacy monitoring cluster alerts #62668 Add action to decommission legacy monitoring cluster alerts #64373

For 8.0.0

• Remove pipelines from Monitoring plugin Remove Monitoring ingest pipelines #77459
• Ensure that index template for the monitoring index is eagerly loaded independent of whether ES monitoring is enabled Move resources creation to init stage #44102 Missing cluster alerts with Metricbeat monitoring if monitoring plugin is disabled #51762 Automatically install monitoring templates at plugin initialization #78350
• Change settings so cluster alerts are not installed by default (but will continue to be managed if explicitly enabled) Change Monitoring plugin cluster alerts to not install by default #79657

For 8.x and beyond

• Deprecate _monitoring/bulk endpoint for removal in 8.x
• Remove _monitoring/bulk endpoint [Stack Monitoring] Remove custom Monitoring Bulk API endpoint #47213
• Remove internal collectors [Stack Monitoring] Remove internal collectors #47214
• Remove exporters [Stack Monitoring] Remove exporters #47215
• Remove watcher cluster alerts
• Remove the monitoring plugin, if possible

[elasticmachine]

Pinging @elastic/es-core-features (:Core/Features/Monitoring)

[dakrone]

Internal monitoring has been deprecated for quite a while, and we're no longer doing any active development on it. I'm going to close this issue.