[8.19] (backport #8429) Add docker image name template and renamed fips cloud specs

[mergify]

What does this PR do?

This PR adds FIPS artifacts elastic-agent-cloud-fips* alongside the existing elastic-agent-fips-cloud* to ease scripting around fips/non-fips capable image variants.

Introduced a new optional packaging spec setting docker_image_name_template where a go template can be specified to control the rendered name of the docker image.

Why is it important?

Simplify scripting around fips/non-fips capable docjer image names.

Checklist

• I have read and understood the pull request guidelines of this project.
• 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
• [ ] I have added an integration test or an E2E test

Disruptive User Impact

How to test this PR locally

Related issues

Questions to ask yourself

• How are we going to support this in production?
• How are we going to measure its adoption?
• How are we going to debug this?
• What are the metrics I should take care of?
• ...

---

This is an automatic backport of pull request #8429 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 79dec1c has failed:

On branch mergify/bp/8.19/pr-8429
Your branch is up to date with 'origin/8.19'.

You are currently cherry-picking commit 79dec1cc2.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   dev-tools/packaging/packages.yml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   dev-tools/mage/dockerbuilder.go
	both modified:   dev-tools/mage/pkgtypes.go

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[elasticmachine]

Pinging @elastic/elastic-agent-control-plane (Team:Elastic-Agent-Control-Plane)

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarQube

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: fd5864f

History

• 💔 Build #22167 failed fa8541b
• 💔 Build #22163 failed beba904
• 💔 Build #22158 failed 31d4094

cc @pchila