[8.x] Set default pipelineBus to v1

[kaisecheng]

fix: #16654

Release notes

Set the default pipeline to pipeline implementation to PipelineBusV1

What does this PR do?

Set the default PipelineBus to v1 in Logstash v8. PipelineBusV2 will be the default in Logstash v9.

Why is it important/What is the impact to the user?

Currently v2 has a chance to block shutdown

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files (and/or docker env variables)
• I have added tests that prove my fix is effective or that my feature works

Author's Checklist

• [ ]

How to test this PR locally

Related issues

• closes Pipeline to pipeline should default to PipelineBus V1 #16654
• relates p2p: less synchronization in pipeline bus #16194

Use cases

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Logs

[elastic-sonarqube]

Quality Gate passed

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[elasticmachine]

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