[8.19](backport #44452) Provide a consistent non-global metrics API to beats and beat receivers

[mergify[bot]]

A refactor to allow beats and beat receivers to use consistent metrics registries without relying on the process-global default defined in elastic-agent-libs. When initialized under Beats, the locally passed registries reference the existing global ones, for compatibility while the remaining global references are removed. When initialized in a Beats receiver, new non-global registries are created, and the receiver will report only fields that have been migrated away from the global references.

This PR should cause no user-visible changes outside the beats receivers. Within the beats receivers, it migrates most Filebeat/Metricbeat metrics variables so they can be used within the receivers.

Checklist

• [x] My code follows the style guidelines of this project
• [x] 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~~
• [x] 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.~~

---

This is an automatic backport of pull request #44452 done by [Mergify](https://mergify.com).

[mergify[bot]]

Cherry-pick of 1b1a4c6f8879e8926d1590085364a9997b599a4c has failed:

On branch mergify/bp/8.19/pr-44452
Your branch is up to date with 'origin/8.19'.

You are currently cherry-picking commit 1b1a4c6f8.
  (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:   filebeat/beater/filebeat.go
	modified:   filebeat/input/filestream/internal/input-logfile/metrics.go
	modified:   filebeat/input/filestream/metrics_integration_test.go
	modified:   filebeat/input/journald/environment_test.go
	modified:   filebeat/input/v2/compat/compat.go
	modified:   filebeat/input/v2/input-cursor/input.go
	modified:   filebeat/input/v2/input-cursor/manager_test.go
	modified:   heartbeat/monitors/mocks.go
	modified:   libbeat/api/routes.go
	modified:   libbeat/beat/beat.go
	modified:   libbeat/beat/info.go
	new file:   libbeat/beat/monitoring.go
	modified:   libbeat/cmd/instance/beat.go
	modified:   libbeat/monitoring/inputmon/httphandler.go
	modified:   libbeat/monitoring/inputmon/input.go
	modified:   libbeat/monitoring/inputmon/input_test.go
	modified:   libbeat/monitoring/report/elasticsearch/elasticsearch.go
	modified:   libbeat/monitoring/report/elasticsearch/elasticsearch_test.go
	modified:   libbeat/monitoring/report/report.go
	modified:   libbeat/outputs/elasticsearch/client_integration_test.go
	modified:   metricbeat/beater/metricbeat.go
	modified:   metricbeat/mb/module/configuration.go
	modified:   metricbeat/mb/module/example_test.go
	modified:   metricbeat/mb/module/factory.go
	modified:   metricbeat/mb/module/runner_test.go
	modified:   metricbeat/mb/module/wrapper.go
	modified:   metricbeat/mb/module/wrapper_internal_test.go
	modified:   metricbeat/mb/module/wrapper_test.go
	modified:   packetbeat/beater/packetbeat.go
	modified:   winlogbeat/beater/winlogbeat.go
	modified:   x-pack/filebeat/input/benchmark/input.go
	modified:   x-pack/heartbeat/scenarios/framework/framework.go
	modified:   x-pack/libbeat/cmd/instance/beat.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   filebeat/input/filestream/environment_test.go
	both modified:   filebeat/input/v2/compat/compat_test.go
	both modified:   x-pack/libbeat/cmd/instance/receiver.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

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Pinging @elastic/sec-linux-platform (Team:Security-Linux Platform)

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