bump index name version

[klacabane]

Summary

Before 8.x, metricbeat's monitoring packages used to index events with a legacy schema when xpack.enabled: true setting was activated. This logic is gone in 8.x and only serves to target a specific index format. Since we now index events with a different schema we also need new mappings for the Stack monitoring UI to be compatible.

These new mappings can't conflict with the current one so they target a version 8 of the .monitoring-{product}-{version} pattern. This change bumps the version to target those.

Additional context elastic/kibana#121251

[elasticmachine]

Pinging @elastic/stack-monitoring (Stack monitoring)

[elasticmachine]

Pinging @elastic/integrations (Team:Integrations)

[elasticmachine]

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• Start Time: 2021-12-17T11:33:40.501+0000

• Duration: 103 min 14 sec

• Commit: 9ff5d93

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Skipped	2550
Total	12478

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