[8.x](backport #4168) Replace most context.TODO calls, comment on other Background and TODOs

[mergify]

What is the problem this PR solves?

Replace use of context.TODO and context.Background from most use cases

Design Checklist

• I have ensured my design is stateless and will work when multiple fleet-server instances are behind a load balancer.
• I have or intend to scale test my changes, ensuring it will work reliably with 100K+ agents connected.
• I have included fail safe mechanisms to limit the load on fleet-server: rate limiting, circuit breakers, caching, load shedding, etc.

Checklist

• 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

Related issues

• Closes context.TODO and loggers #3087

  ---

  This is an automatic backport of pull request Replace most context.TODO calls, comment on other Background and TODOs #4168 done by Mergify.

[mergify]

Cherry-pick of cf41f38 has failed:

On branch mergify/bp/8.x/pr-4168
Your branch is up to date with 'origin/8.x'.

You are currently cherry-picking commit cf41f38c.
  (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:
	new file:   changelog/fragments/1733164018-Replace-use-of-context.TODO.yaml
	modified:   cmd/fleet/main.go
	modified:   internal/pkg/action/dispatcher.go
	modified:   internal/pkg/api/handleArtifacts.go
	modified:   internal/pkg/api/handleCheckin.go
	modified:   internal/pkg/api/handleFileDelivery.go
	modified:   internal/pkg/api/handleUpload.go
	modified:   internal/pkg/api/metrics.go
	modified:   internal/pkg/api/server.go
	modified:   internal/pkg/bulk/engine.go
	modified:   internal/pkg/cache/cache.go
	modified:   internal/pkg/config/config_test.go
	modified:   internal/pkg/config/env_defaults.go
	modified:   internal/pkg/config/env_defaults_test.go
	modified:   internal/pkg/file/uploader/finalize.go
	modified:   internal/pkg/limit/listener.go
	modified:   internal/pkg/profile/profile.go
	modified:   internal/pkg/server/agent.go
	modified:   internal/pkg/server/fleet_integration_test.go
	modified:   internal/pkg/state/reporter.go
	modified:   internal/pkg/testing/esutil/datastream.go
	modified:   internal/pkg/testing/esutil/esutil.go
	modified:   internal/pkg/testing/esutil/ilm.go
	modified:   internal/pkg/testing/esutil/index.go
	modified:   internal/pkg/testing/esutil/template.go
	modified:   internal/pkg/throttle/throttle.go
	modified:   internal/pkg/throttle/throttle_test.go

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   internal/pkg/config/config.go
	both modified:   internal/pkg/server/fleet.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

[mergify]

This pull request has not been merged yet. Could you please review and merge it @michel-laterman? 🙏

[mergify]

This pull request is now in conflicts. Could you fix it @mergify[bot]? 🙏
To fixup this pull request, you can check out it locally. See documentation: https://help.github.com/articles/checking-out-pull-requests-locally/

git fetch upstream
git checkout -b mergify/bp/8.x/pr-4168 upstream/mergify/bp/8.x/pr-4168
git merge upstream/8.x
git push upstream mergify/bp/8.x/pr-4168

[elastic-sonarqube]

Quality Gate passed

Issues
4 New issues
1 Fixed issue
0 Accepted issues

Measures
0 Security Hotspots
76.1% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube