Update menus.en.yaml (DataDog#8461)

Update custom_metrics.md (DataDog#8453)

Updating "Tracking custom metrics" part.  top 500 custom metrics → top 5000 custom metrics
https://docs.datadoghq.com/account_management/billing/usage_details/#top-custom-metrics

Update metrics_namespace.md (DataDog#8460)

Adding translations (DataDog#8440)

Merge pull request DataDog#8443 from DataDog/zach/gitlab-cache

Zach/gitlab cache

Merge pull request DataDog#8456 from DataDog/FatineBts-patch-1

[Typo] APM Required Info

Update python.md (DataDog#8452)

Updated wording for systemctl services (DataDog#8450)

* Updated wording for systemctl services

* Add suggested wording change

Remove the debug environment variable from systemctl (DataDog#8446)

Add instructions for .NET Core on Linux with systemctl (DataDog#8444)

* Add instructions for .NET Core on Linux with systemctl

* Update content/en/tracing/setup/dotnet-core.md

Co-authored-by: andrewardito <62575351+andrewardito@users.noreply.github.com>

* fix typos

Co-authored-by: andrewardito <62575351+andrewardito@users.noreply.github.com>