[release/9.0-staging] Fix wrong alias-to for tvos AOT packs in net8 workload manifest

[akoeplinger]

Customer Impact

• Customer reported
• Found internally

While working on #110477 I noticed that we made two mistakes when adding the net8 workload manifest.

1. Microsoft.NETCore.App.Runtime.AOT.Cross.net8.tvos-arm64 uses the wrong alias-to so on an arm64 macOS host you'd get the x64 package and vice versa
2. Microsoft.NETCore.App.Runtime.net8.osx-arm64 refers to the Mono runtime package instead of the CoreCLR one.

This will only show up if you target e.g. net8.0-tvos using a net9 sdk and as far as I know the SDK should fetch the correct package during build, it just won't be pre-downloaded to the sdk packs folder.

Regression

• Yes
• No

This was introduced in 2d7fe94 but it's only a regression in the sense that it happens when you use the net9 sdk to target net8.0-tvos

Testing

Tested locally by modifying the WorkloadManifest.json and observing the correct pack is installed.

Risk

Low. This just changes the workload manifest for net8 when using a net9 sdk.