nixos/filebeat: Improve options

[felbinger]

Description of changes

The implemented nixos options for filebeat could be improved.

I had trouble finding a way to disable the elasticsearch output in the first place, which was the main reason to open this pr, see: #280535

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[felbinger]

@SuperSandro2000 Is it possible to set default values for attrOf submodule, which can be set like outputs.<name>.enable ?
I tried setting the default value (see code), but I don't think this is going to work.

Do you see any other way to accomplish this without removing the default option (which again is a breaking change)?

Is there also a simpler solution to filter the outputs attrs to only get the enabled (see code)?

[SuperSandro2000]

I don't think the module system will now properly merge this.

I think this could be similar to 490ba58 but not fully sure.

[felbinger]

Looks like it is working. I tested a couple configurations and just had one issue with an assertion. Also this is nothing I changed in this commit, it was just changed due to new formatting standard which has been introduced in #326407.