chore(ci): reusable container image generation

[rogercoll]

Changes

In the Elastic's fork, we want to start including our OpenTelemetry Agents distributions (Node, Java and .NET) into the demo's services. To do that, we will need to modify the service's Dockerfiles and publish our modified versions. This PR moves the build-images.yml to a reusable CI file component_build-images.yml and moves the repository check into its new push execution build-images.yml.

It also parametrizes the repositories name (ghcr and dockerhub).

Related issue: https://github.com/open-telemetry/opentelemetry-demo/issues/1405

Merge Requirements

For new features contributions please make sure you have completed the following essential items:

~~* [ ] CHANGELOG.md updated to document new feature additions~~ ~~* [ ] Appropriate documentation updates in the docs~~ ~~* [ ] Appropriate Helm chart updates in the helm-charts~~

Maintainers will not merge until the above have been completed. If you're unsure which docs need to be changed ping the @open-telemetry/demo-approvers.