[8.17](backport #6180) Add config generation benchmark

[mergify]

What does this PR do?

Add a benchmark for config generation in the coordinator. We specifically profile having a lot of Pods from the Kubernetes provider, which is something that has recently become a problem, and which the configuration generation pipeline doesn't deal with very well. I used test data from a real environment where the problems outlined in #5991 and #5835 could be reproduced.

From profiling the live agent experiencing these issues, this benchmark covers the most expensive parts, so it should be representative.

Current results on main:

goos: linux
goarch: amd64
pkg: github.com/elastic/elastic-agent/internal/pkg/agent/application/coordinator
cpu: 13th Gen Intel(R) Core(TM) i7-13700H
BenchmarkCoordinator_generateComponentModel-20    	      30	  36693604 ns/op	35875285 B/op	  810689 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      28	  37448198 ns/op	35886685 B/op	  810670 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      27	  37193185 ns/op	35867024 B/op	  810650 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      22	  47190285 ns/op	35865402 B/op	  810526 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      31	  59598417 ns/op	35889725 B/op	  810712 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      31	  38748898 ns/op	35890251 B/op	  810715 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      28	  38338585 ns/op	35878466 B/op	  810667 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      27	  38126388 ns/op	35889337 B/op	  810647 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      31	  37849710 ns/op	35884377 B/op	  810712 allocs/op
BenchmarkCoordinator_generateComponentModel-20    	      27	  37850712 ns/op	35882968 B/op	  810648 allocs/op
PASS
ok  	github.com/elastic/elastic-agent/internal/pkg/agent/application/coordinator	24.152s

Why is it important?

I'd like to make some improvements to the configuration generation in the coordinator, and want a straightforward way of demonstrating their impact.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas

Related issues

• Related Elastic agent uses too much memory per Pod in k8s #5835 Memory Consumption Issue with Elastic Agent on Kubernetes with high number of resources #5991

---

This is an automatic backport of pull request #6180 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of b3bb590 has failed:

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Changes to be committed:
	new file:   internal/pkg/agent/application/coordinator/testdata/config.yaml
	new file:   internal/pkg/agent/application/coordinator/testdata/variables.yaml

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   internal/pkg/agent/application/coordinator/coordinator_test.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

[elastic-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarQube