Remove release packages layout creation from gather-drop

[MilenaHristova]

Epic: https://github.com/dotnet/release/issues/740

Remove the release packages layout creation from gather-drop. The layout creation is moved to the release infra with https://github.com/dotnet/release/issues/828 Don't copy packages into folders, the output of gather-drop should be 2 folders - Shipping and NonShipping and a file manifest.json

Previous output layout of gather-drop:

├── manifest.json
├── shipping/
│   ├── assets/  
│   └── packages/  
├── nonshipping/
│   ├── assets/  
│   └── packages/  
└── publish_files/
    └── nuget/
        ├── identities/
        |   ├── aspnetcore.csv
        |   ├── efcore.csv
        |   ├── emsdk.csv
        |   ├── linker.csv
        |   ├── runtime.csv
        |   ├── sdk.csv
        |   ├── templating.csv
        |   └── windowsdesktop.csv
        ├── nukgs-all-just-for-reference.txt
        ├── nukgs-aspnet.txt
        ├── nukgs-core.txt
        ├── sympkgs-all.txt
        ├── nupkgs/
        └── sympkgs/

New output layout:

├── manifest.json
├── shipping/
│   ├── assets/  
│   └── packages/  
└── nonshipping/
     ├── assets/  
     └── packages/  

Release Note Category

• [x] Feature changes/additions
• [ ] Bug fixes
• [ ] Internal Infrastructure Improvements

Release Note Description

Removed release packages layout creation from gather-drop

[MilenaHristova]

There are 2 changes in gather-drop that are part of this

• removing the CreateReleasePackagesLayout function
  • we can either remove this completely or keep it behind a option like --create-release-packages-layout
  • we should make sure no one except the release infra relies on the layout
• replacing the list of targets from the manifest.json assets with a single target - in GetTargetPaths
  • the first target location is the "release packages layout" location
  • it's used only to copy files to that layout
  • in general it's confusing that we have 2 targets as a list and it's not clear which is used for what

[MilenaHristova]

PR: https://github.com/dotnet/arcade-services/pull/3495

I didn't find any use of publish_files folder in dotnet org on GitHub but to be sure @mmitche, do you know if anyone uses gather-drop apart from the release infra ?

[mmitche]

Nothing that I know of. And if they use it, then not publish_files

[MilenaHristova]

PR for the documentation: https://github.com/dotnet/arcade/pull/14762

[MilenaHristova]

This is done with https://github.com/dotnet/arcade-services/pull/3495