observabilitySRE: docker rake tasks

[yaauie]

Release notes

[rn:skip]

What does this PR do?

• Adds various observabilitySRE rake, make, and gradle tasks for creating docker artifacts
• Includes rejection-point for filtering out files, and an injection-point for adding files to the tarball.
• Fairly significant delta from how this patch would apply to main since main has a major refactor -> https://github.com/elastic/logstash/pull/16599/files

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

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

How to test this PR locally

./gradlew --stacktrace artifactDockerObservabilitySRE

NOTE: until #17271 is merged, the docker image will include the files from removed gems.

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

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

See analysis details on SonarQube

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: b8307cf

Failed CI Steps

• 🥼 Integration Tests / part 1
• 🥼 Integration Tests / part 1