Fix binary caching push failures (set BinaryProviders::nuget_repo) & remove unused field

[VelocityRa]

BinaryProviders::nuget_repo wasn't getting set anywhere, even though BinaryCache::push_success() uses it.
Also removed BinaryConfigParserState::nuget_repo_info which was unused.

Without this change, pushing any package into my GHE nuget cache resulted in these kinds of errors (started happening 3+ months ago on my Ubuntu 20.04 GitHub Actions runner):

Pushing vcpkg-cmake-config_x64-linux.2022.2.6-vcpkga66b0ae909b0dfb01b299ab9de46b1e919ddf11d8565c40906a893993d6b3ce8.nupkg to 'https://nuget.git.[redacted]'...
  PUT https://nuget.git.[redacted]
WARNING: No destination repository detected. Ensure the source project has a 'RepositoryUrl' property defined. If you're using a nuspec file, ensure that it has a repository element with the required 'type' and 'url' attributes.
  BadRequest https://nuget.git.[redacted] 283ms
Response status code does not indicate success: 400 (Bad Request).

Potential reviewer: @BillyONeal

[BillyONeal]

Thanks!