[tests] Follow-up work for E2E testing with workloads

[radical]

dotnet/runtime - workload testing

• dotnet/runtime - avoid using nuget restore for installing the manifest as that does not work with PackageType='dotnetplatform'
• dotnet/runtime - Support adding package source mapping
• dotnet/runtime - Support custom nuget source name for built-nugets inserted into test nuget.config
• WIP - [workload-testing] Misc improvements runtime#99392

aspire

#2746

• Remove the nuget-local, and PackageType='' workarounds
• Remove the in-line task used for patching nuget.config for helix
• Removing from this issue to be followed up independently [testing] Follow up to enabling docker based tests on windows #2826
• move InstallWorkload* target to a non-test project (WIP)
• E2E tests - container name can be different from the resource name being used, eg pomelo vs mysql ([tests] EndToEnd - add test scenarios #3113)
  cc @eerhardt @joperezr

[radical]

All the items here are complete now.