Add aerospike input in agentbaet-spec.yml

[herrBez]

Proposed commit message

Add entry for aerospike/metrics input in agentbeat spec

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.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Disruptive User Impact

This should not have disruptive impact on users

Author's Checklist

How to test this PR locally

Related issues

• [New Integration] Aerospike integrations#9344

Use cases

Monitor Aerospike via Elastic Agent, create an (experimental) Aerospike integration

Screenshots

Logs

[mergify]

This pull request does not have a backport label.
If this is a bug or security fix, could you label this PR @herrBez? 🙏.
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.

[elasticmachine]

Pinging @elastic/elastic-agent-data-plane (Team:Elastic-Agent-Data-Plane)