Remove prebuilts for 5.0 targeting packs

[mthalman]

The following prebuilts were added in dotnet/installer#15933 to compensate for a change in NuGet:

• Microsoft.AspNetCore.App.Ref.5.0.0
• Microsoft.NetCore.App.Host.linux-arm64.5.0.17
• Microsoft.NetCore.App.Host.linux-x64.5.0.17

The change was introduced by dotnet/installer#15905.

Related build that shows prebuilt failures: https://dev.azure.com/dnceng/internal/_build/results?buildId=2142871&view=results (internal link)

In order to remove these as prebuilts, we either need to have these targeting packs added to SBRP or a compensating change made in NuGet that prevents these from showing up as prebuilts.

[MichaelSimons]

I think this was a result of these changes - NuGet/NuGet.Client#5098.