Change filebeat azure eventhub input to use processor v2 as default

[kaiyan-sheng]

Proposed commit message

This PR is to change Filebeat azure eventhub input and related modules to use processor v2 as the default.

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
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in ./changelog/fragments using the changelog tool.

Disruptive User Impact

For users that are currently still using v1 processor version, they need to add this into their config manually for the new version to work for v1.

How to test this PR locally

Test cases I would like to cover for this change are:

1. Default (no processor_version)
2. Set processor_version to v1 for backwards compatibility
3. Set processor_version to v2

Do we need to test the migration path on Beats?

Related issues

This PR takes care of the Beats side of elastic/integrations#15703. We will need to make the same change in the Integrations.

[botelastic]

This pull request doesn't have a Team:<team> label.

[github-actions]

🤖 GitHub comments

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Just comment with:

• run docs-build : Re-trigger the docs validation. (use unformatted text in the comment!)

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @kaiyan-sheng? 🙏.
For such, you'll need to label your PR with:

• The upcoming major version of the Elastic Stack
• The upcoming minor version of the Elastic Stack (if you're not pushing a breaking change)

To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit
• backport-active-all is the label that automatically backports to all active branches.
• backport-active-8 is the label that automatically backports to all active minor branches for the 8 major.
• backport-active-9 is the label that automatically backports to all active minor branches for the 9 major.

[kaiyan-sheng]

@zmoog What would be the impact and action here for this breaking change?

[zmoog]

Is this a breaking change? If we can continue to support the connection string with the same setting this should not be.

Are we forced to change the config format, making it incompatible with the existing configs?

[kaiyan-sheng]

Not a breaking change! I think we should use deprecation instead. @zmoog wdyt?